FORENSIC MEDICINE

Topic 2-5
(Postmortem changes and time since death
Mechanical Injuries
Firearm and Explosive Injuries)
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Contents

Postmortem changes and time since death 3

Mechanical Injuries 18
Firearm and Explosive Injuries 36
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DEATH AND ITS MEDICOLEGAL IMPORTANCE

Thanatology is a branch of science that deals with the study

of death. Human life, in a manner of speaking is a brief spell of
existence between two heartbeats, man's first and man's last. Death
is an inevitable reality and in the past was considered to be a simple
and straightforward phenomenon. The doctor would declare a
person dead once he was convinced that there was cessation of life
in the patient. This meant that the patient had stopped breathing, his
heart had stopped beating, there was unresponsiveness, and his body
had turned cold. But this state can also exist, though for a brief
period, when a person is in a state of suspended animation as seen in
the victims of electrocution, drowning, hypothermia, etc. Though
cessation of heartbeat was enough to consider a person as dead in
the past, it is no longer as evidence of death today since the heart is
now able to be substituted with that of a ' just deceased donor' or a
mechanical one. Moreover, modern biomedical innovations like the
resuscitator and cardiac pacemaker have made it imperative to
establish a set criteria by which the moment of death could be
identified. The basic concept is that death is the irreversible loss of
the capacity for consciousness and capacity to breathe. Since both
the functions reside in the brain, the modern concept of diagnosing
death is to identify whether a person's brain is alive or not.

POSTMORTEM CHANGES AND TIME SINCE DEATH

The paramount medicolegal issue in any postmortem examination

relates to the determination of time since death (Postmortem
Interval). This question arises most commonly in cases of
unwitnessed or unreliably witnessed deaths, but may be of crucial
importance even in cases of reliably witnessed 'simultaneous'
deaths. Accordingly, the accurate determination of the postmortem
interval applies not only to civil law, in which ascertaining the exact
time of death is of practical necessity in settling family, social, and
business matters, but also to criminal law, wherein the accurate
determination of the time since death may either exonerate or
inculpate a suspect accused of a particular homicide. Such
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determination is an indispensable component of corpus delicti (i.e.,
the body of evidence which proves the commission of a crime), and
may serve as a basis for deciding whether to extend investigative
effort in a particular line or direction. Therefore it is extremely
important to accurately interpret the changes that occur after death.
For convenience, these changes are being described under the
following headings:
Immediate changes which result in complete and irreversible
cessation of the functions of the brain, heart and the lungs. Muscles
of the body become flaccid, and the corneal reflexes are abolished.
Early changes which take place between the first 12 to 24
hours. They comprise:
 Changes in the skin
 Changes in the eye
 Algor mortis (Postmortem cooling; Chill of death)
 Livor mortis (Postmortem lividity; Рostmortem staining;
Hypostasis)
 Rigor mortis.

Late changes include putrefaction and its modifications, namely

adipocere formation and mummification.
The immediate changes after death mentioned above may also be
seen in cases of suspended animation. Suspended animation is a
state where the metabolic needs of the body are at such low ebb that
the person appears apparently dead. His pulse is not palpable, heart
sounds are not audible, respiratory movements are not visually
perceptible, and reflexes are either absent or not possible to elicit.
The person is not actually dead, and he can be revived in most cases
by resuscitation. Recognizing this condition is important in order to
prevent premature certification of death. Newborn babies and
victims of electrocution, drowning, hypothermia and sedative
poisoning may go into a state of suspended animation.

EARLY CHANGES
Changes in the skin: Elasticity is lost soon after death. Skin that
was translucent in life becomes pale.
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Changes in the eye:
The cornea loses its lustre with the passage of time. It becomes dull,
hazy, and finally opaque and wrinkled. If there is a living will for
the removal of the cornea for transplantation, it should be removed
preferably within half an hour after death.
Intra ocular tension falls so rapidly that by two hours after death, the
tension is nearly zero and the eyeball appears sunken.
If the retina could be viewed through an ophthalmoscope, the
columns of blood in the vessels may be seen to be broken up into
segments, which is referred to as 'trucking'.

Algor mortis (Postmortem cooling; Chill of death): There is a

constant balance between heat production and heat loss during life.
After death, heat production is lost and therefore the body starts
cooling. The dead body loses its heat by conduction, convection and
radiation. Measurement of the rate of cooling helps in estimating the
time since death. When the rate of cooling is plotted on a graph the
pattern of the curve assumes a sigmoid shape.

Fig 6.3 Graphs showing fall in

temperature when: a) an inorganic
body cools; and b) a dead body
cools. (Adapted from Gordon &
Shapiro, Forensic Medicine, 1982.)
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The body surface starts losing heat rapidly, but the core body
temperature does not alter until a gradient is established between the
core body temperature and the surface. As there is no significant
change in the core body temperature for sometime which may be
upto 2 to 3 hours after death, an initial plateau is seen. When once
the gradient is established between the core body temperature and
the surface, the rate of cooling is approximately proportional to the
difference in temperature between the body and the surface. This
aspect is in accordance with the Newton's law of cooling. That
means after the initial plateau the curve dips down progressively
before it becomes nearly flat at the bottom. The curve may even rise
before becoming flat due to heat produced by putrefactive changes.
The preferred site for measuring the inner core body temperature is
either the rectum or the abdominal cavity. A chemical thermometer
with graduations from 0 to 50° Celsius is introduced deep inside the
rectum (to about 10 cms), or alternatively, the thermometer may be
kept in contact with the undersurface of the liver through a slit made
in the anterior abdominal wall in the right hypochondrium. At the
same time, the environmental temperature is also measured. The
time since death is then calculated (after taking two readings at an
interval of one hour), by the following formula:

Normal body temperature -

Rectal temperature
= Time since death
Rate of fall of temperature/hour

There are a number of variables:

1. The body temperature at the time of death is presumed to be
normal. This may not be the case. In fact in some cases, there is a
slight rise in the temperature of the body after death. This is known
as postmortem caloricity, and may be seen in bodies which at the
time of death had suffered violent muscular contractions, or in the
case of asphyxial deaths such as strangulation, or septicaemic
deaths, strychnine poisoning, pontine haemorrhage.
2. If the environmental temperature is extremely cold, the process of
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cooling of the body is hastened, while in very hot climates the body
may not cool at all.
3. Obesity lessens the heat loss, as fat is a bad conductor of heat.
4. Ratio between the body surface and the body mass - children and
old people cool more rapidly.
5. Presence of thick clothing at the time of death slows the rate of
heat loss.

In addition to the commonly employed sites for measuring

the body temperature mentioned above, other sites have been
proposed by various investigators, including the trachea, nasal
cavity, middle ear cavity, etc. Electronic thermometer and
thermocouple have been employed in the place of chemical
thermometer by some investigators.
Livor mortis (Postmortem lividity; Рostmortem staining;
Hypostasis): With the stoppage of functions of the heart after death,
active circulation of blood in the body ceases. The blood which is
fluid in nature, gradually settles down in the toneless capillaries of
the dependent parts of the body, seen externally as patches of
purplish discolouration through the skin. This settling of blood in
the dependent parts is in accordance with the law of gravity. Thus if
the body is in supine position the postmortem lividity will be seen
on the back. In deaths due to hanging, lividity is seen on the hands,
feet, and the lower parts of the face above the ligature. In drowning
where the body usually floats with the back facing up and the limbs
hanging down, the lividity is seen over the limbs, abdomen and the
face. Distribution of the lividity thus is useful in indicating the
position of the body after death.
Those parts of the body which are in actual contact with the surface
they lie on, do not show the colour as the toneless capillaries are
pressed by the weight of the body. Such areas are known as areas of
contact flattening. Thus in the body which is lying supine,
postmortem lividity is not seen over the shoulder blades, buttocks,
calves, etc. If the deceased was wearing a tight collared shirt, a band
of pale area may be seen around the neck where lividity does not
develop, and this could be confused with a strangulation mark by an
inexperienced person. Proper interpretation of such findings is
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important.
Postmortem lividity begins as mottled patches ranging from
1 to 2 cms in diameter. These patches gradually increase in size with
the passage of time and coalesce with each other till they become
one uniform area of staining. Though the time of the appearance of
these patches is variable, they are generally seen 2 to 3 hours after
death. If the position of the body is altered, these patches gradually
disappear, and appear in the new dependent part. If the body is left
undisturbed for a certain length of time, lividity becomes well
developed and fixed, and does not alter in position even with
subsequent alteration in the position of the body. This was till
recently thought to be due to clotting of blood in the blood vessels.
In fact, the word 'fixation' itself is erroneous. If the position of the
body is altered after 'fixation' and left in the new position for some
longer time, the intensity of the lividity gradually fades, even though
some colour, probably due to haemolysis staining the tissues, may
sometimes remain in the primary position. Blood is always found
fluid in capillaries and venules, and this blood is responsible for
postmortem lividity. Thus, clotting of blood is not responsible for
the colour. 'Fixation' is an apparent phenomenon. If pressure is
applied over the area of lividity, it blanches. After 6 to 8 hours, the
lividity does not blanch, when it is said to be 'fixed'.
Colour of the lividity in certain cases helps in arriving at the cause
of death. For example, it is cherry red in carbon monoxide
poisoning, bright red in cyanide poisoning, blackish in opiate
poisoning, etc.
Patches of lividity may sometimes be seen over non-dependent
areas. The possible mechanism for this is the squeezing of column
of blood in the deeper veins against gravity, towards the skin
surface, by the muscles developing rigor mortis. Such patches could
be mistaken for contusion marks. This confusion is easily resolved
by making an incision over the discoloured area.
If it is contusion, staining of the tissue is seen which can not
be washed off, while if it is lividity, the blood oozes out from the
freshly cut blood vessels, and the fresh stain can be easily washed
off with water. If still doubt persists, microscopic examination of the
tissue from the suspected area clinches the diagnosis.
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As the process of formation of postmortem lividity is purely a
physical phenomenon, it is seen in the dependent parts of the
internal organs also. It is important to bear this in mind, lest the
appearance of it in the organs may be mistaken for some significant
condition of medicolegal bearing.

Note:
 PM lividity disperses with the onset of putrefaction.
 PM lividity may not develop at all if the body is tossed and
turned continuously as seen in fast flowing waters of rivers
or the sea.
 PM lividity cannot be appreciated well in dark coloured
subjects.
 PM lividity may not be appreciable even in fair skinned
bodies if they have bled profusely or were severely anaemic.

Significance of lividity in postmortem clocking is not very

reliable. However, scientists have tried instruments utilizing light, to
measure PM lividity and its application to establish the time since
death, with some significant correlation between them.
Evaluation of PM lividity using colorimeter-measuring system has
also been tried with some success in postmortem clocking.

Rigour mortis:
During life, muscles are supple, and in a slightly contracted state.
After passing through a phase of primary flaccidity soon after death
during which they are totally relaxed, the muscles over a period of
time, gradually stiffen. This stiffening is known as rigor mortis.
Rigor mortis affects all the muscles in the body, both skeletal and
smooth.
Rigor mortis is a physico-chemical phenomenon. Recalling
one's memory of the elementary structure of the muscle is necessary
to understand the mechanism of its formation. A muscle mass is
made up of a number of bundles of long fibres. Each muscle fibre in
the bundle consists of densely packed myofibrils, which are the
contractile elements. These myofibrils are made up of two protein
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filaments, actin and myosin. Separation of actin and myosin are
responsible for extensibility and softness of the muscles. Coming
together of these actin and myosin filaments, which result in
contraction is dependent on the energy provided by adenosine
triphosphate (ATP).

Fig. 1. Schematic arrangement of

myosin and actin filaments in the
muscle fibre. Adapted from
Gradwohl’s Legal Medicine. 1976.

Constant supply of ATP is maintained in life. Failure of resynthesis

of ATP after death results in the muscles becoming hard and rigid.
However, some amount of ATP is still available after death till the
glycogen reserve lasts. When once this glycogen reserve is depleted,
there is no more ATP available, and the contractile elements are
converted into dehydrated, stiff, gellike mass resulting in the
muscles themselves becoming hard and rigid.
Rigor mortis becomes noticeable first in the eye lids, then the
muscles of the face, jaw and neck. Then it is seen to affect the upper
limbs, thorax, abdomen and the lower limbs. Though rigor mortis is
basically due to chemical changes, the physical aspect is responsible
for this apparent proximo-distal progression, viz. (videlicet), smaller
muscles having less glycogen reserves than the larger muscles are
first to be affected.
It is generally considered that by the first 12 hours after
death, rigor affects the whole body. It is retained for another 12
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hours, and passes off in the next 12 hours with the onset of
putrefaction. This Rule of 12, also known as the March of rigor, is
only a generalization of the time since death. Rigor passes off in the
same order in which it made its proximo-distal progression. With
the passing away of the rigor, the muscles once again become
softened. This is the phase of secondary flaccidity.
Another condition, rarely seen but commonly talked about, is
cadaveric spasm or instantaneous rigor, where instead of primary
flaccidity after death, the muscles usually belonging to small groups
go into a sudden state of stiffening. This condition though of
unknown cause, when seen, is usually associated with violent deaths
coupled with emotional disturbance at the time of death, as in
drowning (where grass or weeds may be clutched in the hands),
suicide by shooting (where the weapon may be tightly grasped in the
hand), etc.
Other conditions that result in the body becoming stiff after
death include thermal deaths, and gases evolved during putrefaction.
The stiffening of the body in deaths due to burns (heat stiffening) is
due to coagulation of muscle proteins, while in exposure to severe
cold (cold stiffening), the body becomes stiff due to freezing of the
subcutaneous fat and the water content in the body, forming icicles.
Gases evolved during the putrefactive process also stiffen the body
(gas stiffening), but poses no problem in distinguishing it from rigor
mortis.
Note:
 Application of force results in breaking of rigor, which does
not set in again when once broken.
 As rigor is a chemical phenomenon, any condition that
depletes ATP fast, will hasten its early development. For
example, violent muscular contractions at the time of death
due to epilepsy, strychnine poisoning, tetanus, electrocution,
etc.
 In robust, healthy young individuals, it appears late because
of good glycogen reserve in the muscle mass.
 As rigor mortis is not functionally related to the nervous
system, it can develop in paralyzed limbs also.
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 As rigor is also not dependent on blood supply, it develops
even in amputated limbs.
 If a body is frozen soon after death, and such a body is
brought back to normal environmental temperature, rigor
mortis which had been arrested till then, will appear
subsequently. Estimation of time since death from such
thawed bodies becomes erroneous.
 Apart from postmortem clocking, rigor mortis helps in
identifying any alteration in the position of the body, if the
position in which the body has undergone rigor is
incompatible with the position in which it was discovered at
the scene.

LATE CHANGES
Putrefaction
Onset of putrefaction initiates the breakdown of complex
organic constituents of the body into simpler inorganic substances.
Such breakdown of complex structure is facilitated by autolysis and
bacterial action, while the destruction of the body tissues by various
fauna expedites the process of disintegration.
Autolysis: The digestive action of various enzymes released
by the cells after death leads to softening and liquefaction of tissues.
Soft tissues like the brain, lungs, pancreas, gall bladder, and
stomach are affected earliest. Architectural patterns of the organs
are lost. Maceration of the dead foetus inside the uterus is a classical
example of autolytic putrefaction. This means the process of
autolysis is independent of any bacterial action. It is an aseptic
chemical process.
Bacterial action: Any condition conducive for rapid
bacterial growth results in early onset of putrefaction. Bacteria
disseminate and multiply fast after death, as stagnant blood offers an
excellent medium for their growth. Apart from the normally
inhabiting bacteria of the body, bacteria from outside also may enter
the body through open wounds. These bacteria generally comprise
streptococci, staphylococci, escherichia coli, proteus species, and
clostridium welchii.
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While autolysis produces limited gross change, bacterial action is
the major component of putrefaction
Changes occurring due to putrefaction: Greenish
discolouration in the right iliac fossa is the earliest external
manifestation of the onset of putrefaction, which occurs around 12
to 24 hours after death. This is the area where the caecum lies, the
contents of which are more fluid and rich in bacteria. Hydrogen
sulphide produced by the bacteria acts on the haemoglobin (that has
now become extracellular due to haemolysis), to produce
sulphhaemoglobin. This imparts the greenish hue. With the passage
of time this greenish discolouration, which is very obvious in fair
skinned bodies, subsequently spreads to the abdomen, and also
makes its appearance in the chest, face, and the limbs. Coalescence
of these coloured areas results in the entire body becoming greenish
or greenish-black.

Later, in about 36 to 48 hours, a network of veins becomes visible in

the form of a characteristic mosaic like pattern (marbling), over
various parts of the body like the root of the neck, shoulder, etc.
This results from staining of the vessel walls due to diffusion of
haemoglobin.
By the time the colour changes become visible externally, evolution
of gases would have started internally. These gases possess very
unpleasant smell. They include hydrogen sulphide, ammonia,
carbon dioxide, carbon monoxide, methane, etc. These gases by
themselves are not of any medicolegal significance, but the pressure
effects they produce when they accumulate in sufficient quantity are
so much as to bring about gross changes in the appearance of the
body. Evolution of gases results in a) ballooning effects and b)
dispersion of p.m. lividity.
Ballooning effects: Gases easily collect in the hollow
viscera resulting in their voluminous expansion. The stomach and
the intestines which balloon out, increase the intra abdominal
pressure resulting in distension of abdomen, and pushing of the
diaphragm upwards. Lungs are squeezed by this pressure, and froth
oozes from the mouth and nostrils. The gases not only accumulate in
the hollow viscera, but also penetrate into every tissue and organ.
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Soft tissues of the body like the breast, scrotum, periorbital tissues,
etc., increase in their size enormously. Eyeballs protrude out of the
sockets, the cheeks puff out, and so also the lips. The tongue
protrudes through the mouth, and on exposure to air becomes dark
in colour. The facial features alter so much that even the
resemblance to a normal human face is lost. At this stage,
identification by external features becomes extremely difficult even
to the closest relatives.
Percolation of putrefactive gases into the undersurface of the skin
results in the epidermal layer ballooning out, which resembles
blisters caused by scalding. In contrast to protein rich fluid present
in the blisters caused by scalding, putrefactive blisters contain only
air.
The epidermal layer from the hands and feet slip off like glove and
stocking. It is important to retain and preserve this part of the skin as
it can yield a full set of fingerprints that may help in establishing
identity.
Increased pressure inside the abdomen may result in the expulsion
of foetus in the case of a pregnant deceased. Uterus and rectum may
protrude out due to pressure.
Though the evolution of gases may commence as early as 18 hours
after death, a full-blown picture to develop may take 48 to 72 hours.
Dispersion of postmortem lividity. Evolution of gases
moves the blood in the blood vessels. If the blood is clotted, it now
liquefies, and haemolysis takes place. Movement of this blood
results in dispersion of p.m lividity in any direction. Therefore
assessment of the position of the body at the time of death, based on
lividity at this stage becomes difficult.
Entomology of the cadaver.
Emanating foul smelling gases of putrefaction attract various
insects. There are eight successive waves of invasion from the
beginning of putrefaction right upto skeletonisation. Initially, two-
winged flies predominate, but later there will be involvement of
several other kinds of insects including beetles.Two-winged flies
such as flesh flies, house flies, etc., lay their eggs in about 18 to 36
hours (sometimes as early as 6 to 10 hours). Mostly these eggs are
laid in the mucocutaneous junctions such as lips, nostrils, anus,
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vagina, or even in open wounds.
The eggs hatch into larvae (maggots) within 12-24 hours. These
larvae are very voracious eaters and they grow in size upto 4 to 5
days, during which time they devour the tissues and hasten the
process of disintegration of the body. The maggots then enclose
themselves inside shell-like structures (pupae), which in another 4 to
5 days break open to release young flies.

The study of the life cycle of these insects, which infest dead bodies,
is known as Forensic Entomology.
The role of the doctor while doing autopsies on such maggot-
infested bodies is only to pick up these maggots, preserve them
properly, and send them to a qualified entomologist for species
identification. Maggots immersed in boiling absolute alcohol die
instantly in extended position, which facilitates measurement of
their length.
Colliquative putrefaction: In 3 to 5 days after death, the
nails and the hair become loose and can be pulled off with ease. The
teeth become loose and can be pulled out from their sockets. The
abdomen and the thorax may burst open. The sutures on the skull in
children loosen, the liquefied brain matter oozing out through these
deficiencies. With further progression of putrefaction, from 5 to 10
days, colliquative putrefaction ensues, resulting in the tissues and
organs being converted into a soft, thick, black, pultaceous mass,
totally losing their architecture. However even at this stage, organs
such as the prostate and non-gravid uterus can be identified, as they
resist putrefaction, thus helping in the identification of the sex.
This liquefied unrecognizable pultaceous mass gradually falls off
from the bony attachments leaving the skeleton exposed. In 1 to 3
months, complete skeletonization occurs.
Sometimes the environmental conditions may arrest the progression
of putrefaction and may deviate it to either adipocere formation or
mummification.
Adipocere (Saponification; Grave wax): This arrests the
further progression of putrefaction. Adipocerous change is due to
hydrogenation and hydrolysis of body fat.
The prerequisites for adipocerous change of the body fats
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include
 abundant body fat,
 humid climate,
 still air,
 warm temperature, and
 bacteria producing fat-splitting enzymes, like Clostridium
welchii.

Thus a body lying on damp soil, in a shady place, with optimum

environmental temperature, and no free air current blowing over it,
undergoes adipocerous change. Adipocere has the appearance of
rancid butter, and gives off a sweetish but disagreeable smell.
Transformation of the body fat into adipocere is usually seen over
areas such as cheeks, breasts, buttocks, or limbs, though rarely the
whole body is affected. It takes generally about 3 weeks for
adipocere to develop fully.
As the progression of putrefaction is arrested, the facial features are
recognizable, which helps in identification of the deceased by
friends or relatives. Similarly, as the wounds are also preserved
without much alteration, the weapons used (and to a certain extent
the cause of death), can be identified. The approximate time since
death can also be estimated.
Mummification: In hot and dry climate, where there are
warm air currents freely flowing over the body, putrefactive process
becomes arrested and the body becomes mummified due to
dehydration and desiccation of the tissues and the organs. The skin
is dark and tightly adherent to the skeletal frame. Mummification
usually requires 3 to 6 months. A mummified body does not
emanate any foul smell.
Mummification helps in identification, as the general facial features
are preserved. It also helps in recognizing the presence of wounds,
and the estimation of the approximate time of death and place of
death.

ESTIMATION OF TIME SINCE DEATH

The time since death or postmortem interval is the period
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that has elapsed between death and the actual performance of the
postmortem examination. The significance of such estimation of the
time has been mentioned at the beginning of the lecture. Though the
exact time of death can rarely be estimated on the basis of autopsy
findings, an approximate range can usually be deduced by
intelligent interpretation of the various changes that take place after
death. Estimation of the time since death within a narrow range is
possible only in the early period. Once putrefaction sets in, this
range becomes wider. However, entomological study can help in
narrowing the range considerably.
Evidence for estimating the time since death generally falls under
the following three categories:
Corporal evidence - that which is present in the dead body.
Environmental and associated evidence – that which is present in
the vicinity and general surroundings of the deceased.
Anamnestic evidence - that which is based on the deceased's
ordinary habits, movements and day to day activity.
Assessing the time of death by environmental evidence and
anamnastic evidence is mostly the responsibility of the investigating
officer in India. The doctor is generally not involved. The doctor's
assessment of time since death is almost exclusively dependent on
the evidence that can be deduced by the findings on careful
postmortem examination. Naturally he relies upon the changes that
take place after death such as postmortem cooling, postmortem
lividity, rigor mortis, and putrefactive changes, bearing in mind all
those factors that alter the outcome of these individual changes.
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Mechanical Injuries

Trauma is an insult to the state of well being. This insult can be

physical or mental. Usually, one is accompanied or followed by the
other in negligible or substantial degree. Physical trauma may manifest
itself as a functional change, or structural (anatomical) change, or
both. The kind of physical trauma which causes structural (anatomical)
change is called an injury. Injury may be associated with loss of
tissue, or without recognisable loss (e.g., redness, oedema). An injury
which is associated with loss of tissue is called a wound. In other words,
all wounds are injuries, but all injuries are not wounds. However,
injury and wound are often described as being synonymous.

Injuries can occur due to natural causes (e.g., diabetic ulcer), or due to
unnatural causes which may be physical (e.g., heat, cold, electricity,
radiation, etc), chemical (e.g., corrosives), or mechanical (e.g.,
weapons such as knife, stick, etc). A mechanical injury can be
adequately defined as "Damage to any part of the body due to the
application of mechanical force". The damage referred to is loss of
tissue.

CLASSIFICATION OF MECHANICAL INJURIES

■ Abrasion
■ Contusion
■ Laceration
■ Incision
■ Puncture (stab)
■ Fracture

Some books mention Punches, Kicks and Bite marks as separate

entities in the classification due to difference in mechanism of
production. However, this is incorrect, since punches (fist blows)
and kicks are only methods of injury infliction, and not really injury
types, while a bite mark is nothing but an abrasion, bruise or
laceration, depending on the severity of infliction. Punches and
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kicks (especially with shod feet) usually result in bruises, and
occasionally lacerations or fractures.

Abrasion
An abrasion is the loss of superficial layers of skin or mucous
membrane due to mechanical force. Because of the corrugated nature
of dermoid papillae, abrasions usually involve the corium of dermis.
Since the blood vessels are confined to dermis, such involvement of
corium seems to be the reason for the common occurrence of bleeding
in abrasions. There is also oozing of lymph, which dries up after death
making the abrasion firm, leathery, or parchment-like.

Mechanism of occurrence: The mechanical force which causes an

abrasion is either friction (sliding), or pressure (compression) applied
on the body surface. Usually both these elements are present, with
one predominating over the other. Friction-predominant abrasions are
called tangential abrasions, while those which are compression-
predominant are referred to as pressure abrasions.

Tangential Abrasion: A tangential (frictional) abrasion is referred to as a

linear abrasion or scratch if it is in the form of a linear mark caused
by a narrow, sharp object. A wider mark caused by a broad, rough
surface is a brush abrasion or graze.

1. Linear abrasion (scratch)

This is produced by frictional (sliding) movement of a sharp object
such as a finger nail, pin, thorn, etc. The object causing the linear
abrasion carries the torn superficial layers of skin in front of it as it
slides forward. This heaping up of superficial layers, often visible at
the concluding end of a linear abrasion, is an indicator of the direction
of movement of the causative agent.
2. Brush abrasion (graze)
This is produced when a rough object scrapes over the skin, or when
the skin moves against a broad, rough surface (e.g., fall on a road).
The terminal end of injury often shows a serrated border with piling
of torn layers of skin, again giving a fair indication of the direction
of sliding movement.
 20
Pressure Abrasion: This is caused by pressure of an object on the
skin. When the impact is vertical, the epidermis gets crushed, and an
imprint of the impacting object is stamped upon the surface. Such an
injury produces a replica of the patterned surface of the causative
object, and is called an impact abrasion (e.g., radiator grill
impression on the skin of a victim of vehicular impact). In the
absence of an impacting force, if there is merely sustained pressure,
the resulting abrasion can still reflect the pattern of the object, and is
referred to as a contact abrasion (e.g., ligature mark of hanging or
strangulation). In such patterned abrasions, the pressure of the object
is mainly vertical, with the frictional (tangential) force being
negligible. As the element of frictional force gradually increases,
the abrasions begin to fail to exhibit the weapon pattern and are
referred to as nonpatterned abrasions. Depending on the presence
and extent of crushing, a contused area can surround these abrasions
to such an extent that in some cases, the contused area will be more
marked than the abrasion, which is then called an abraded contusion.
Alternatively, if the abraded part is more prominent, it is more
appropriately called a contused abrasion.

Other Abrasions: Abrasions can be induced after death. They are

called postmortem abrasions. They are quite common, and can
occur due to mechanical force (e.g., dragging the body after death)
or by animal action (e.g., ant bite). Even the normal procedures of
post-autopsy reconstruction and handling in the mortuary may cause
dermal changes simulating abrasions, especially after washing with
hot water. While an abrasion caused during life is covered by scab
due to coagulation of blood and lymph, and is associated with signs
of inflammation, a postmortem abrasion does not demonstrate these
features. In fact it usually appears pale and dry. Ant bite marks are
pale and irregular in shape, and are seen mainly in moist regions such
as the areas around the eyes, nose, mouth, genitalia, and axilla.
Abrasions produced immediately before or after death may be
difficult to differentiate even by microscopic examination.

An abrasion fabricated on the body by oneself, or with the help of

another person, is called fabricated abrasion. In the former case,
 21
only accessible parts of the body are involved such as face, hands,
etc. The motive for such fabrication can be serious or trivial.

Nappy abrasions constitute a special variety of abrasion seen in

infants due to excoriation of skin over areas usually covered by a nappy
(groin and buttocks). They may be confused with antemortem violence
when viewed at autopsy, unless the pathologist is vigilant. These
abrasions generally appear yellowish or yellowish-brown, and lack
apparent antemortem reaction.
Repair and healing: Healing involves two phenomena - contraction
of the wound, and replacement of lost tissues. When fresh, an abrasion
is bright red in colour. Scab forms by 12 to 24 hours. When fully
formed, a scab is red in colour, and is moist, but it becomes reddish
brown and dry by about 2-8 days. Abrasions heal from the periphery
by new growth of epithelial cells. Ordinarily the scab falls off by
about 7-8 days, leaving a pale area which may persist for a few days
or weeks. A rough estimate of the age of an abrasion can thus be made
from these features. Earlier stages (before scab formation) can be
assessed by histology. Infiltration of polymorphonuclear cells in a
perivascular formation signifies that the wound is 4-6 hours old. At 12
hours, the wound shows three layers - a surface zone of fibrin and red
cells, a deeper zone of polymorphonuclear cells, and a third layer of
damaged, abnormally staining collagen.

Medicolegal significance: An abrasion indicates the site of contact

with an object. Occasionally, an abrasion may be the only external
indication of a deep-seated injury. Abrasions are normally simple
wounds. They are actually three dimensional, but for practical
purposes they are considered to be two dimensional. The type of
abrasion may reveal as to whether the manner of contact was a sliding
one or compressing one. The pattern (if present), can help to some
extent in deducing the nature of the object, while the stage of healing
process could help in determining the time of occurrence. Patterned
abrasions are especially helpful in identifying the exact offending
agent, for e.g., the exact nature of vehicle involved in a "hit and run"
case. However, the determination of age of an abrasion is usually only
approximate and is seldom accurate.
 22
The exact site of an abrasion can sometimes give valid
information about the nature of crime (e.g., abrasions around the nose
and mouth suggest smothering, while those around breasts and genitalia
may suggest sexual assault). Abrasions on a suspected assailant may
be the result of a struggle, and suggests evidence of resistance put
forth by the victim. It is advisable to look for foreign material over
abrasions (e.g., presence of mud particles indicates a fall in a muddy
area).

Contusion
A contusion is an extravascular collection of blood that has leaked from
blood vessels damaged by mechanical impact of a blunt nature, without
loss of continuity of tissues. A contusion is also referred to as a bruise.
The blood vessels involved are usually small arteries, veins, or
capillaries. Contusions are usually situated in the subcutaneous tissue,
but can also occur in various internal viscera.

The term ecchymosis is used if a contusion is smaller than a few

millimeters in size, while pinpoint contusions are generally referred to as
punctate contusions or petechiae. However, the latter term is usually
restricted to haemorrhages resulting from bursting of congested
capillaries, as in asphyxia, or bleeding points in the skin due to
coagulation disorders, rather than those seen in trauma, since the
nature of production is different.

Mechanism of occurrence: The extent of effusion of blood resulting

from damage to blood vessels depends on several factors such as the
site of wound (effusion will be greater in lax tissues such as periorbital
area), thickness of skin (effusion is lesser if the dermis is thick, as in
the palms and soles), resilience of the area (effusion is minimal in the
well yielding anterior abdominal wall), sex (females contuse more
easily than males due to higher amount of adipose tissue), and age
(children and aged individuals are more susceptible than young
adults). Elderly people bruise easily due to increased fragility of blood
vessels. The degree of effusion is also directly proportional to the
vascularity of the area, and the amount offeree applied. Diseases such as
haemophilia, scurvy, and leukaemia can aggravate effusion. A bruise
 23
will be less prominent if it is situated in deeper tissues.

Blood escaping from ruptured vessels usually percolates along the lines
of least resistance. Hence, it is easily influenced by gravity. The site of a
contusion therefore does not necessarily indicate the site of application
offeree, e.g., black eye in head injury. A "black eye" can be caused by
a direct injury, or by gravitation of blood from a wounded scalp, or
from a fractured orbit. Contusions appearing at a site remote from the
site of application of force are called percolated contusions or
ectopic bruises. A deeply situated bruise may manifest externally
only after several hours or days. Such a bruise is called a "come-out
bruise." This may be due to haemolysis, wherein the freed
haemoglobin stains the tissues more and more densely as time elapses.

On certain occasions, the shape of a bruise may give valuable

information about the causative object. Bruises caused by finger tips
over the neck in throttling represent one such example. A lash by a
whip produces a bruise in the form of double lines with an intervening
space approximately equal to the width of the whip. Such bruises are
called patterned bruises.

Sometimes, flat objects such as belts produce characteristic tramline

contusions manifesting as two parallel linear contusions separated by a
relatively pale, undamaged section of skin. Occasionally, rod shaped
objects may also be responsible. They occur because at the site of
impact the blood is squeezed out from vessels without any leakage
(due to lack of damage to the vessel walls), while, at the edges, the
vessel walls are torn because of stretching; as a result there is leakage
of blood. This phenomenon may also be responsible for the
spherical/disc shaped contusions seen in strangling by bare hands,
(resulting from pressure of finger tips).

The size of a contusion may roughly correspond to the object causing

it. This gives some clue regarding the weapon employed. Thus a
contusion caused by a stick is longer than it is broad. Its width usually
corresponds to the diameter of the stick. With lapse of time however,
the contusion may appear larger in size than it originally was, due to
 24
continued extravasation of blood and development of oedema.

Repair and healing: After a lapse of some time, the red blood
corpuscles in a bruise will begin to disintegrate by haemolysis,
liberating haemoglobin, which in turn gets broken down into
haemosiderin, haematoidin and bilirubin, by tissue enzymes and
histiocytes. These pigments impart certain colour changes to a bruise
which can be visualised, especially in the case of fair complexioned
individuals. To begin with, the injury is red in colour, turning bluish in
a day, and brownish over the next 3 days due to haemosiderin. It turns
greenish over the subsequent 3 days (haematoidin), and yellowish in
the final 2 days (bilirubin). At the end of a fortnight, the original
normal colour of the skin is restored, since these pigments get
removed by phagocytosis. In subconjunctival haemorrhage, due to
diffusion of atmospheric oxygen, these colour changes may not be
noticeable.

Postmortem lividity (hypostasis) in the early stages can mimic a

contusion, posing problems in medicolegal interpretation. The
important differentiating points are summarised in Table 1.

Table 1. Differences Between Bruise And Postmortem Lividity

Bruise Postmortem lividity

1. Cause Rupture of vessels and Engorgement of vessels

extravasation of blood due to pooling of blood

2. Site Anywhere in the body Only in dependent parts

3. Surface Elevated No elevation

4. Colour Variable, depending on Normally purple

the age
 25

5. Incision Shows extravasated Blood oozes out of cut

blood in the cut tissues vessels which can be
which cannot be washed easily washed off
off

6. Histology Signs of inflammation No signs of

present inflammation

Contusions can be produced after death, and are referred to as

postmortem contusions.
This is particularly likely when moderate force is applied over those
areas where the skin is immediately subjacent to underlying bone (e.g.,
forehead). A severe blow to the body within a few hours of death can
produce contusions in other parts of the body also, especially over an
area of postmortem lividity. However such contusions are devoid of
swelling, and do not demonstrate inflammatory reaction. Their edges
appear sharply demarcated.

Medicolegal significance: A contusion need not necessarily indicate

the exact site of contact with a blunt weapon, since it can appear at an
area remote to the application of force. The size of a contusion may be
smaller or greater than the weapon producing it. However, it can give
some clue about the contact of a body with an object, and depending on
the site of occurrence, to the nature of crime (e.g., contusions in and
around the nose and lips suggest smothering). In several cases, the
nature of the object used, and the degree of force applied can be
reasonably presumed.

But the exact nature of the object is usually difficult to ascertain, since
blood spreads diffusely around the margins of the contusion. Colour
changes can help to deduce the time of occurrence. Contusions of
markedly different colours on different parts of the body of the same
individual suggest different times of occurrence, and are indicative of
chronic abuse (for e.g., battered baby syndrome). Since contusions
sometimes become evident after a delay of variable period, a second
examination is always advisable, whether the victim is alive or dead.
 26
Intradermal contusions however, constitute an exception to this
general rule as they are superficial - lying just under the epidermis. In
such a case, there may be good correlation between the contusion seen
and the characteristics of the causative object.

Contusions are three dimensional, but in a living victim, the depth

cannot normally be measured.

If there is any doubt as to whether a contusion is antemortem or

postmortem in nature, it is imperative that it be subjected to
histopathological examination, which will reveal antemortem
characteristics such as evidence of vital reaction, if the injury
occurred before death.

Laceration
It is a type of mechanical injury where there is a rupture or tear of
skin or deeper tissues, or both, due to application of blunt force.
Lacerated injuries are three dimensional with length, width and depth,
and often have abraded margins, and irregular, contused edges. Since
blood vessels are crushed, bleeding is usually not severe. However,
substantial bleeding can occur if blood vessels get torn partially.
Foreign particles derived from the weapon or impacting surface are
frequently present in the wound. The interior of the wound contains
bridging strands of tissue which can be visualised clearly with a hand
lens. The depth may not be uniform throughout the injury.

Classification: Lacerated injuries can occur from splitting, stretching,

grinding, or compression. Accordingly they are classified as:
■ Split laceration (incised-looking laceration)
■ Stretch laceration
■ Grind laceration (avulsion)
■ Cut laceration
■ Tear

Split Laceration: In this type, the skin gets split due to compression
between the weapon and underlying bone. The edges often appear clean
cut on cursory inspection. Hence these injuries are also called incised-
 27
looking lacerations. However, a hand-lens examination will reveal
contusion of edges and bridging of tissues. Common areas of
involvement include scalp, lower jaw, shin, etc.

Stretch Laceration: Here the skin gets stretched to a breaking point

resulting in a laceration at that site. For example, pressure over the
thigh which stretches the skin towards the knee can cause a laceration
along the inguinal line.

Ordinarily, unless great force is used, most lacerations require a firm

base to act as an anvil for the skin and underlying tissues to be pinned
against. But this is not true for a stretch laceration.

Grind Laceration (Avulsion): In this type, there occurs a separation of

skin from underlying tissues due to the shearing or grinding action of a
weight, for e.g., the wheel of a heavy vehicle.

Cut Laceration: This type of laceration results from the cutting action
of a weapon which is not very sharp, for e.g., a broken glass piece. It is
a lacerated wound with profound and distinct contusion of edges. While
incised wounds divide hairs cleanly, lacerations cause some hairs to be
driven into the interior.

Tear. As the name suggests, this type of laceration results from

tearing of tissues due to a relatively sharp force, which is not sharp
enough to incise the tissues.

Other Types:
1. Patterned laceration - Lacerations usually do not reproduce the
shape of the injuring object. However, rarely the shape is
recognisable, as in the case of a hammer blow to the scalp. But,
calculation of the exact size of striking surface in such cases can be
misleading.
2. Postmortem laceration - Lacerated injuries may be produced by
terrestrial or aquatic animal action (rat, fish, crab, etc.) on corpses.
Absence of vital reaction will assist in distinguishing them from
antemortem lacerations. The edges may also shaw characteristic
 28
evidence of 'nibbling' or 'gnawing'. A running vehicle or train can
cause extensive postmortem lacerations of a dead body lying in its
path.
Repair and healing: Lacerated wounds often get infected, thus delaying
the healing process. As they do not exhibit uniform healing pattern, age
estimation is difficult and unreliable. Healing is by second intention. It
begins as phagocytosis to remove debris, followed by filling of the
defect by granulation tissue. Specialised tissues lost are repaired, and
epithelium regenerated to cover the surface. A permanent scar is
therefore inevitable. The time frame will depend upon the extent and
severity of the laceration.

Medicolegal significance: Areas of the body that are commonly the site
of lacerations are those with underlying bony support, such as over the
eyebrows, on the scalp and face, or over knees, shin, etc., whilst they
are less common on areas of the body that are softer such as the
buttocks. Lacerations are usually accidental or homicidal. Self-inflicted
lacerations are uncommon. Foreign particles in these wounds may help
to identify the causative object. Grease, mud, etc., may be seen in
wounds of traffic accidents.
The exact type of lacerated injury may provide a clue to the nature of
occurrence. In the case of avulsions, the direction of force can often be
ascertained. The site of the injury may provide some clue about the cause
of death, for e.g., lacerations of internal mucosa of lips may suggest
smothering. Lacerated wounds of face constitute grievous hurt
because of permanent disfiguration.

Incision

An incision or incised wound is a clean-cut separation of skin or

deeper tissues (or both), caused by the sharp cutting edge of an object,
without loss of substance. The commencement of the wound is usually
deep, gradually becoming shallower, and finally tailing off towards the
end. This tailing of the wound indicates the site of withdrawal of the
weapon from the body, suggesting the direction in which the wound
was inflicted. The wound is generally straight and shows maximum
 29
retraction of the edges at the centre. In other words, the wound "gapes",
because of which the width of the wound is greater than the width of
the weapon causing it. The gaping is more if the incision is made at
right angles to the "lines of cleavage" (Lines of Langer), and much less
if it is parallel to these lines (Fig. 2). The edges of the wound are clean
cut and may be everted. Ordinarily there is no bruising of the margins.
An incised wound is necessarily longer than it is deep. It bleeds freely,
as blood vessels are cleanly cut and not crushed.

Fig. 2. Lines of Langer

Classification: An incision produced by a light cutting weapon is
smooth with minimal bruising of margins. Heavy cutting weapons such
as an axe or cleaver produce distinct contusion of the edges, and the
resulting injury is sometimes referred to as a chop wound. Incised
wounds produced over wrinkled skin may appear as lacerations, due to
irregularity of edges, e.g., in the scrotum. A hand lens examination will
help to differentiate them as incised wounds. Such wounds are
sometimes called lacerated-looking incised wounds.
Repair and healing: In the case of an incised wound with very
little damage to tissues on either side of the cut, healing occurs
without delay, if the edges are apposed properly. Small blood vessels
which are cut get occluded by thrombosis. Fibrin precipitated locally
will then link the two edges. Coagulated blood on the surface forms a
 30
scab and helps to keep the wound clean. This occurs within 12-24
hours. Over the next few days, capillaries proliferate to bridge the gap,
and fibroblasts secrete collagen. In 3-5 days, vessels are thickened, and
many of them get obliterated, which is followed by scar formation. This is
usually complete by about the 6th day. The scab over the wound then
falls off, leaving behind a soft, tender, reddish scar, which in the course
of weeks or months becomes whitish and firm. Infection can however
delay the healing process.
Medicolegal significance: Incised wounds invariably point to the use
of a cutting weapon, (light or heavy). The length, width, or depth of an
incised wound usually do not correspond to the length, thickness or
width of the cutting object. Tailing gives an indication of the
direction of movement of the cutting edge. Also, the site may suggest
the possible motive, intent, or even the mental status of the assailant.
For e.g., incised wounds concentrated over the genital area reveal a
sex-related motive. Homicidal incised wounds sometimes suggest
the disturbed mind of the assailant, which may vary from cold fury to
irrational psychosis.
Table 2. An overview of incised, lacerated, and stab wounds
Incision Laceration Stab
Causative Sharp object Blunt object Pointed object
agent
Edges Clean-cut Ragged Clean-cut, and
often everted
due to withdrawal
of weapon
Dimensions Length more Length more Depth more than
than depth than depth length
Haemorrhage Usually Usually not Variable
profuse profuse
Margins Bruising Bruising Usually absent
may or may always
not be present
present
Hairs Clean-cut Crushed or Clean-cut, crushed,
torn or torn
 31
Stab (Puncture)
Stab wounds are piercing wounds produced by sharp-pointed objects
(e.g., dagger, ice pick, sharpened bamboo stick, etc). The depth is
necessarily greater than the surface length.
Stab wounds are divided into penetrating wounds, if they
terminate in tissues, organ, or cavity, and perforating wounds, if
they transfix them (through-and-through wounds). In the former,
there is only one surface wound, while in the latter, there will be two
separate surface wounds, one caused by the entry and the other by the
exit. External bleeding may be slight, but internal bleeding can be very
profuse.
In perforating wounds, the wound of entry is usually larger than the
wound of exit, because weapons used for stabbing usually taper
towards the tip. The edges of the wound of entry are inverted, while
they are everted in the wound of exit. Clothes may be pushed into the
wound of entry. The direction in which the wound has been inflicted
can be deduced by joining the wounds of entry and exit.

Medicolegal significance: The external appearance of a stab wound

may sometimes give a clue regarding the kind of weapon used in
inflicting it (Fig. 3.). Thus, a penknife which has one sharp edge and a
thicker, blunt edge, produces a wound which is usually wedge shaped.
On the other hand, a double-edged weapon such as a dagger will usually
produce an elliptical wound.

Fig. 3. Different shapes of stab wounds

produced by different types of
weapons
 32
If the weapon used to stab enters the skin obliquely, the edge of the
wound on the side from which the weapon has entered becomes
"bevelled", while the other edge overhangs the wound. From this, the
direction in which the wound was inflicted may be ascertained.

Stab wounds may be homicidal, accidental, or suicidal. The presence

of such wounds in inaccessible parts can exclude suicide. The terminal
ends of the injury may be sharp cut, square shaped, or rounded. If both
ends are sharp-cut, in all probability the weapon used was a double-
edged one, even though a single-edged weapon can sometimes
produce such an appearance due to splitting, or if the weapon possesses
a curved beak. It can also occur if a single-edged weapon is tilted
while being withdrawn. Bruising around the stab wound may indicate
that the weapon had been inserted up to the hilt.

The depth of the wound may give an indication of the minimum length
of the weapon used, provided the entry wound and the termination of the
wound track are situated in non-yielding areas. If the punctured wound
has made an entry through a yielding site (e.g., abdominal wall), or ends
up in a cavity or a collapsible organ (e.g., lung), the deduction of depth
becomes a matter of conjecture.

The depth of the wound can be greater than the length of the weapon
over yielding sites such as abdominal wall due to the compression of
the wall downwards during the thrust, and its subsequent return to the
normal position when the pressure is withdrawn. Similarly, collapse of
lungs after sustaining stab injury over the chest (particularly on the
front or lateral sides) may lend itself to wrong interpretation of the
length of the weapon, since the distance between the chest wall and
surface of lungs will be increased due to collapse.

The length of the entry wound may be equal to the breadth of the
stabbing weapon. However, it is usually lesser by 0.2 to 0.3 cm if the
skin is elastic, while it may be greater if rocking of the object occurs
during the course of stabbing. The width of the entry wound is usually
greater than the thickness of the weapon due to gaping.
 33
Fracture
Fracture of a bone is defined as breakage of a bone due to direct or
indirect force.

Classification

Direct Fractures
1. Focal fracture
This is otherwise known as tapping fracture and results from a
small force applied to a small area. It is usually transverse. Injury
to overlying soft tissues is minimal. Typically seen in regions
such as the forearm or leg where two bones lie adjacent to each
other, only one of the two bones being fractured, for e g., while
warding off blows during an attack.

2. Crush fracture
It results from application of a large force over a large area, and is
typically comminuted in type, i.e. (id est), fragmented. Injury to
surrounding soft tissues is usually extensive. If two bones lie
adjacent to each other, both are involved, for e.g., bumper fracture
of the tibia and fibula in a pedestrian who has been hit by a car.

3. Penetrating fracture
It results from application of a large force over a small area. Bullet
injury to a bone is a classical example of this type of fracture.

Indirect Fractured
1. Traction fracture
It results when a bone is pulled apart by traction, e.g., transverse
patellar fracture due to violent contraction of quadriceps.

2. Angulation fracture
It occurs due to bending of a bone. The concave surface of the bend
is compressed, while the convex surface is put under traction
resulting in breakage.
 34
3. Rotational fracture
Here the bone is twisted to produce a spiral fracture.

4. Vertical compression fracture

In this type, there is an oblique fracture of a long bone such that the
hard shaft of the bone is driven into the cancellous portion. It is
sometimes encountered in the distal femur of a vehicle passenger
when there has been a collision, and his knee has impacted
violently against the dashboard.
5. Angulation-compression fracture
Here, the fracture line is curved, with an oblique component due to
compression, and a transverse component due to angulation.

Repair and healing: Healing of a fracture depends upon the age and
nutritional status of the individual. In general, cancellous bone unites
faster than cortical bone. There are 5 stages involved in the healing
process
■ Haemorrhagic phase
■ Proliferation phase
■ Callus phase
■ Consolidation phase
■ Remodelling phase

In the haemorrhagic phase, there is haemorrhage at the site of fracture.

In the proliferative phase, a collar is formed around the fractured ends
by proliferation of cells from periosteum and endosteum. In the callus
phase, cellular elements give rise to osteoblasts and chondroblasts
which produce a matrix of collagen and polysaccharide, impregnated
with calcium. This is called "callus." In children, the callus is visible
radiologically within 2 weeks of the fracture. In the consolidation phase,
the callus is transformed into mature bone which takes about 4-6
weeks in children, and approximately 3 months in adults. In the final
remodelling phase, the mature bone is remodelled.

Medicolegal significance: Fracture of a bone, however trivial,

constitutes grievous hurt according to law. From a study of the exact
type of fracture an idea about the causative force can be estimated,
 35
i.e., whether the force was direct or indirect, rotational or angular,
etc. The site of fracture may help to indicate the cause of death, for
e.g., fracture of hyoid bone suggests throttling. The time of
occurrence of a fracture can be estimated roughly from the stage of
the healing process.

Firearm and Explosive Injuries

 36
FIREARM INJURIES

Ballistics is the science dealing with the study of firearms and

ammunition. It includes the study of the effects of discharging a
firearm, projectile motion, and factors affecting the efficacy of firing.
While a detailed knowledge of these is not essential for a forensic
pathologist, he must nevertheless acquire an elementary knowledge of
firearms for proper interpretation of the wounds caused by them.

Sub-Divisions
1. Proximal (Internal) Ballistics: The study of firearms and
projectiles is called proximal ballistics.
2. Intermediate (External) Ballistics: The study of the motion of a
projectile after being ejected from the firearm till the time it hits the
target is termed as intermediate ballistics.
3. Terminal (Wound) Ballistics : The study of injuries produced by
firearms is referred to as terminal ballistics, and is the exclusive
realm of a forensic pathologist.

Proximal Ballistics

In simple terms, a firearm is a mechanical device equipped to create an

explosion, which in turn forces out a projectile at high velocity in order
to hit a target. The term ammunition refers to the materials used for
causing the explosion, along with the projectile. One complete round
of ammunition is called a cartridge. The projectile is pushed out
through a cylindrical tube which is called a barrel. If the barrel is
grooved internally, it is a rifled firearm, otherwise it is a smooth bore
firearm.

CARTRIDGE

A cartridge consists of an outer case in which the explosive is stored

together with the chemicals required to ignite it, and the projectile.
The explosive is called propellant or gunpowder, while the igniting
chemical is called detonator or primer. The projectile is either a bullet
or pellets (shot). The former is used in rifled firearms, and the latter in
 37
smooth-bore firearms.

Cartridge = Case + Detonator + Propellant + Projectile (missile)

(primer) (gunpowder) (bullet or shot)

1. Cartridge case
In rifled firearms, the cartridge case is made of an alloy of copper
and zinc, while in smooth bore firearms it is made of a special type
of paper or cardboard.

In both types the shape is cylindrical. One end of the case is closed
with a plate of brass and is called the base, while the other end is
open. The cartridge case helps not only to keep the contents in
place, but also provides a waterproof cover for them and protection
against deterioration. The base of the cartridge is invariably
rimmed, but in automatic weapons there is a groove instead of the
usual projecting rim.

2. Detonator
It is also known as "primer". Common ingredients comprise
mercury fulminate (or lead azide), potassium chlorate, and
antimony sulfide. These chemicals are capable of rapid
combustion. They are stored in a small compartment attached to the
base of the cartridge case called percussion cap which is made of
copper. Hence the detonator is also known as cap composition. In
most of the cartridges the percussion cap is situated near the centre
of the base, and are therefore referred to as centre fire cartridges,
while in a few the whole of the base acts as a percussion cap and
are known as rim fire cartridges.

3. Propellant
This is situated in close proximity to the primer within the cartridge
case. There are three types of gun powder - black powder, semi-
smokeless powder, and smokeless powder. Black powder is a
mixture of 75% potassium nitrate, 15% charcoal and 10% sulphur.
Smokeless powder consists of nitrocellulose alone (single base), or
nitrocellulose combined with nitroglycerine (double base). Semi-
 38
smokeless powder consists of 20% smokeless powder and 80%
black powder. While all types of gun powder produce smoke, the
Smokeless variety does not produce as much smoke as black
powder, and is the most effective type being capable of imparting
higher velocity to the projectile. The ignited primer causes
combustion of gun powder by which hot gases under tremendous
pressure are produced within the closed confines of the cartridge,
propelling out the projectile with great velocity. A single grain of
black powder can produce 200 to 250 cc (cubic centimeter) of gas
composed of carbon monoxide, nitrogen, hydrogen, hydrogen
sulphide, and traces of methane and oxygen, while a grain of
smokeless powder can generate 800 to 900 cc of gas.

4. Projectile
This is usually either a bullet or a bunch of pellets (shot). The
former is used in rifled firearms, while the latter is used in smooth-
bore weapons. Firearms meant to propel projectiles of less than one
inch diameter are called small arms. They may be hand operated,
i.e. (id est), hand arms (e.g., pistol and revolver), or they may be
placed against the shoulder and fired, i.e., shoulder arms (e.g.,
rifle, musket, shot gun, etc). Hand arms are also referred to as side
arms. In country-made firearms, unusual projectiles are often used,
e.g., pieces of glass, cork, wood, nails, stones, etc.

Normally, a bullet is held in the cartridge case by a groove called

cannelure. As a result of the pressure generated by gases, the bullet
gets released, and is pushed through the barrel and out of the muzzle
with great velocity. Bullets are usually made of lead with a coating
of cupronickel alloy. They are invariably conical in shape, in order
to offer least resistance while travelling through air. The tip of a
bullet is referred to as its nose. Depending upon the size of the
bullet, it can be short, medium or large, and as per the shape of the
nose, it can be flat nosed, round nosed, hollow nosed or point nosed.
Pellets used in smooth bore firearms are collectively referred to as
shot. Sometimes slugs may be used instead, which are much larger.
A flat felt-disc or compressed paper or cardboard called wad lies
between the pellets and propellant. It is often called underwad.
 39
There is another wad, termed the turnover wad or top wad, situated
over the lead shot the purpose of which is to keep the shot in place.
Wads not only hold the pellets and gun powder tightly in place,
they also act as a piston sealing the bore effectively, thus
preventing the expanding gases from escaping. This is known as
obturation or sealing of the bore which is of vital importance. In
order to lubricate the bore, wads are often impregnated with grease.
In modern ammunition, plastic is being used increasingly
commonly, and some of the older constituents are no longer present.
Once a firearm has been discharged, the empty cartridge case is left
behind in the chamber devoid of projectile, but with residues of
primer and detonator still present. This is called spent cartridge.
The spent cartridge has to be extracted from the chamber manually,
or it may get ejected automatically (as in automatic firearms).

Figs 9.4 and 9.5 show the longitudinal section of shotgun and rifled
firearm cartridge respectively.
 40
FIREARM

Every firearm has a chamber in which the cartridge is normally

lodged. The chamber leads into a hollow steel tube called the barrel.
The projectile released from the cartridge in the chamber is forcefully
pushed through the barrel by the expanding gases produced by the
explosion of gun powder. The proximal end of the chamber has a
minute hole, through which г. pin moves forward to strike the base of
the cartridge.This striking action produces heat which ignites the primer.
This pin, known as firing pin is activated by a spring connected to a
trigger mechanism. The spring is released on pulling the trigger. The
part which incorporates the firing pin, spring, and trigger is called the
bolt.
Barrel
It is a steel tube of varying length, and may be single or double. The
chamber constitutes the rear end of the barrel, and lodges the cartridge.
This part is called the breech. The front (distal) end of the barrel which
is open to the exterior, is called the muzzle. The term bore refers to that
part of the barrel through which the projectile makes its exit. The
barrel may measure any thing from 2.5cm (1 inch) to 90cms (3 ft).
The tapering portion connecting the chamber with the bore is called the
leed (taper). In rifled firearms, the interior of the barrel is scored by a
number of parallel, spirally twisted grooves called rifling, whereas in
smooth bore weapons the interior surface is smooth. The rifling may
be either clockwise or anti-clockwise. A cross section of a rifled bore
would reveal a series of elevations alternating with depressions
(corresponding to the grooves). The former are called lands. The
bullet is squeezed between the lands as it travels through the bore and
since rifling is spiral, it imparts a spin or rotation to the projectile by
which it acquires a gyroscopic steadiness, preventing it from
wobbling.

In some smooth bore firearms, the barrel becomes narrower towards

the muzzle end. This is called choking. Choking minimises dispersion
of the pellets after they emerge from the barrel. Depending upon the
extent of narrowing, it may be either a, full choke bore or a half choke
 41
bore. A barrel that is not choked is called cylinder bore. In some
firearms (paradox guns), the bore is only partly smooth, while the
remaining part is rifled.

If loading of a cartridge is done through the muzzle end of a firearm it

is called a muzzle loader, and if it is done through the breech it is a
breech loader.
Bolt
This is also called block and is situated towards the breech end of the
barrel. As described earlier it consists essentially of a trigger, which
when pulled releases the spring to activate the firing pin, which
quickly moves forward to strike the base of the cartridge inside the
chamber. The trigger is usually surrounded by a trigger guard to prevent
accidental firing. In addition, there is a safety catch which prevents
the gun from discharging even when the trigger is accidentally pulled.

The block also contains an extractor to remove the spent cartridge, and is
fashioned into a grip or butt around the trigger mechanism, for holding
the firearm. The block can be opened to insert a fresh cartridge into the
chamber manually or automatically. In automatic firearms, the
cartridges are arranged one below the other to form a magazine, which
is attached to the block. If the trigger is pressed and the pressure is
sustained, it will cause the continuous release of all the cartridges
from the magazine until the latter becomes empty. In semiautomatic
firearms, only one cartridge at a time is released each time the trigger is
pulled. In non-automatic weapons, the spent cartridge has to be
extracted manually each time after firing.
Classification of firearms
1. Rifled firearm
a) High velocity: shoulder arms - e.g., rifle automatic weapons -
e.g., machine gun, sten gun
b) Low velocity, hand arms - e.g., revolver, pistol (Fig. 9.6)

2 Smooth bore firearm (Shot gun)

a) Single barrelled or double barrelled
b) Breech loader or muzzle loader
 42
c) Cylinder bore or choke bore

3. Air or gas operated firearm

4. Country made firearm

Fig. 9.6

Pistol
Revolver
a.Exterior view
b. Interior view a. Exterior view
с. Magazine b. Exterior view with
magazine disengaged

Fig. 9.7 Calibration of rifled

firearm
 43

CALIBRE

The calibre of rifled firearms is usually expressed in terms of the inner

diameter of the barrel, in fractions of an inch. Thus, we have the 0.303
and 0.22 rifle, meaning that the calibre is 0.303 of an inch and 0.22 of
an inch respectively. The measurement is made between two
diametrically opposite lands and not between grooves (Fig. 9.7).

The calibre (or gauge) of a shotgun is expressed in terms of the

number of balls of lead which can be made out of 1 pound (450 gms)
of the metal, so that each fits exactly into the bore of the weapon. If
12 balls of the same size can be accommodated, the calibre is referred
to as 12 bore. The other commonly available calibre of shotgun is 16
bore. The actual calibre (in terms of inner diameter of the barrel) of a
12-bore gun is 1.850cm (0.729 inch) while that of a 16-bore gun is
1.685cm (0.663 inch).

Intermediate Ballistics
This is not very important for a forensic pathologist, and is the
specialised field of a ballistics expert.

Terminal Ballistics
Forensic pathologists must have a thorough knowledge about Terminal
Ballistics, which deals with the injuries resulting from firearms.

The wound produced by a projectile (bullet or shot) as it enters the

body is called the entry wound, and that by which the projectile leaves
the body is the exit wound. The path traversed by the projectile
between the entry and exit wounds is called the track. Exit wound is
generally absent in the case of shotgun injury, except in the region of
the head.

RIFLED FIREARM INJURY

Entry Wound (Fig. 9.8)

 44
The distance between the muzzle end of the firearm and the target is
called the range.

This may be
 Contact range, if muzzle end is in contact with body,
 Close range, if the range is within the distance travelled by
flame
 Near range, if it is within the distance travelled by unburnt or
partially burnt gun powder, and
 Distant range, if it is beyond the range of flame, smoke and
gun powder particles.

Fig. 9.8 Shape of entry wound depending on angle of bullet

entry

During the bullet's attempt at perforating the skin while entering, due
to the spin, the edge of the entrance wound may be abraded in the form
of a collar, which is termed the abrasion collar or areola. In some cases
there is contusion instead of abrasion, in which case it is more
appropriately called the contusion collar. The diameter of the entry
hole together with the abrasion collar may give the approximate
diameter of the bullet.

The barrel of a firearm is generally lubricated between use. When such

 45
a weapon is fired, the bullet as it is propelled through the barrel, would
naturally carry this lubricant (grease) on it, which subsequently gets
deposited on the skin around the entrance wound. The spin of the
bullet causes wiping of its surface on the skin while entering. This is
called the grease (or dirt) collar. The abrasion and grease collars
normally measure only about 0.3cm and 0.7cm respectively.

When both abrasion and grease collars are present, the grease collar is
seen as the inner zone, while the abrasion collar constitutes the outer
zone.

Burning (scorching or singeing) of skin and hair result from the

flame that emerges from the muzzle, at the time of firing. Clothing
around the entry wound may also show evidence of burning.

Tattooing (peppering or stippling) results from grains of gun powder

being driven into the skin, each grain acting as a minute missile.
Tattooing is seen on the skin as small, discrete, black specks which
cannot be wiped off. The extent of tattooing will depend on the calibre
of the weapon, the type of powder used, and the range. Tattooing may
be absent if firing has taken place through clothing.

Blackening or smudging results from a superficial deposit of smoke

on the skin. In other words, it is only a carbonaceous deposit on the
skin, and hence can be easily removed by wiping with a wet sponge.
The intensity of smudging will depend on the calibre of the weapon,
the type of powder used, and the range. Thus, the greater the calibre of
the weapon, the wider the area of blackening and vice versa. Similarly,
if black powder is used, the blackening will be more clearly visible,
than if smokeless powder had been employed.

Smudging may be absent on skin if firing has taken place through

clothing. The presence of blackening, especially when smokeless
powder has been used, may not be clearly visible to the naked eye. In
such cases, infrared or ultraviolet photography will help to visualise
it.
 46
Since carbon monoxide is evolved on explosion of gun powder, the
presence of this in the blood of the injured tissues at the entrance
wound imparts a cherry red colour to the tissues.

A lead ring or metal ring around the entry wound results from the
deposition of very small quantities of lead or other metal in the form of
a ring or collar, as the projectile enters the skin. The lead ring can be
appreciated radiologically or by neutron activation analysis.

Firearm wounds are generally easily recognised as such. But

sometimes wounds caused by red hot pokers or a burning pointed stick
may simulate bullet entry. However in these wounds, there will be no
evidence of tattooing or cherry red colour.
Conversely, glancing injuries caused by rifled firearms may be confused
with incised or lacerated wounds.
1 Contact shot
It also known as a point blank shot. A contact wound over a dense
area such as the cranial vault is generally large and cruciate
(cruciform, stellate, or star shaped), due to explosive effects of the
gases liberated. The imprint of the muzzle of the weapon may be
found stamped on the skin. Burning, fouling by smoke, and
tattooing are slight or absent in the adjacent skin, since all the
components of the explosion are driven into the wound. The
tissues are often saturated with carbon monoxide and therefore
cherry red in colour. Cranial contact wounds are generally seen on
the forehead or temple.

Contact wounds over thin bone, chest, or abdomen are usually

circular in shape, and are surrounded by abrasion or contusion
collar. The overall diameter of the hole plus the collar represents the
approximate diameter of the bullet. Surrounding hair is singed. The
muscles around the track of the bullet may be cherry red in colour
due to saturation with carbon monoxide.

2. Close shot
Flame travels approximately up to 7.5 cms in the case of revolver or
pistol, and 15 cm in the case of rifle. The wound appears as a
 47
circular hole surrounded by scorching, singeing, and smudging.
These may be absent if firing has occurred through clothing.
Abrasion collar, grease collar, and tattooing may be present.

3. Near shot
The entry wound is circular or oval in shape. Unburnt powder grains
and small metallic particles travel approximately up to 60 cms in the
case of revolver and pistol, and 75 cm in the case of rifle. In
practical situations, tattooing is seen up to a maximum distance of
about 90 cm. Singeing of hair and scorching are absent. Smudging
can occur up to a range of 30cm. Beyond this it is not seen. Grease
collar and abrasion collar are present.

4. Distant shot
The entry wound is circular with inverted margins. Scorching,
tattooing, and smudging are all absent. Grease collar and abrasion
collar are present. Distant shot suggests a range beyond self-
infliction. The range in any case of gunshot injury can be estimated
accurately by test firing, using the same gun and similar cartridge at
different ranges, and comparing the effects with the wound present
in the victim.

Exit Wound
Exit wounds vary greatly in size, shape, and configuration. They are
usually larger than the corresponding wound of entry. Scorching,
blackening, and tattooing are absent, as also abrasion and grease
collars. Edges are invariably everted.

Salient differences between entry and exit wounds are mentioned in

Table 3.

Table 3. Differences between Entry and Exit rifled firearm injury

Characteristic Entry wound Exit wound
Size Smaller than the Large
diameter of the
 48
bullet
Edges Inverted Everted
Abrasion and Grease Present Absent
Collar
Burning, Blackening, May be present Absent
Tattoing
Bleeding Less More
Fat extrusion Absent May be present
Cherry red colour May be present Absent
Lead ring May be present Absent

Track: This is the path traversed by a projectile inside the body of

a victim of gunshot injury, between the entry and exit wounds. In
the case of low velocity weapons, the track can be devious instead
of straight. An X-ray prior to autopsy will assist significantly in
locating bullets or pellets lodged in the body. When a projectile
traverses through dense tissues such as muscle, liver, or spleen,
shock waves are generated causing tissue damage even at a
considerable distance away from the track.

SMOOTH BORE FIREARM INJURY

Entry Wound

1. Contact shot
The contact shot wound in the case of shotguns is usually a
large, irregular hole, resulting from the explosive blast effect.
The edge of the defect is scorched by flame, and the skin
surrounding it is blackened by smoke, and tattooed by unburnt
powder. An imprint abrasion produced by the muzzle end may
be seen. The shot (comprising a bunch of pellets) passes into the
body as a solid mass. The injured tissue is usually cherry red in
 49
colour. Shotgun injury of the cranium is large and irregular, and
fissured fractures often radiate outward from the margins.

2. Close shot
This produces a circular defect with irregular inverted borders.
The edges are scorched due to flame, and smudged by smoke. A
fairly wide zone of tattooing may surround the edges of the
wound. Tissues often appear cherry red in colour. The pellets
enter the track en-masse. Sometimes a shotgun may discharge
parts of the cartridge case itself, such as fragmented cardboard,
plastic or primer particles. At contact and close ranges, these
may contribute to the wound.

3. Near shot
The wound is circular or oval in shape. Smudging may be
evident around the wound up to a maximum distance of 30 cm.
Sometimes the wad produces mild abrasions if fired within a
range of 30 cm. Tattooing is present over a wide area. The pellets
travel in a compact mass up to a distance of about 45 cm, after which
they begin to disperse. The entry wound is approximately 2.5 cm in
diameter. If the shot enters at an angle less than 90 degrees, the
shape of the wound may become triangular or semi-circular.

4. Distant shot
Beyond a range of 2 metres, there will be no burning or blackening.
Tattooing is also rare. But wad may be present in the wound (up to 5
metre range). The dispersion of pellets becomes significant at
ranges over 2 metres. Thereafter, the spread increases progressively,
and the central defect diminishes in size proportionately. There is
an old rule of thumb which states that the diameter of the spread in
inches is roughly equal to the range in yards multiplied by 1.5. At
distant ranges (beyond 6-10 metres), the central hole may shrink to
nothing. At such ranges the shot may not be lethal and the pellets, if
they do penetrate the skin at all, may lie just in the subcutaneous
tissue.

MEDICOLEGAL ASPECTS OF FIREARM INJURIES

 50
Legally, firearms are classified as dangerous weapons, and mere
possession without license or authority becomes a cognisable offence.

The following constitute some important medicolegal issues in

firearm deaths:
■ The kind of firearm used
■ The range of firing
■ The direction of fire
■ The place from where firing took place
■ The cause of death, and
■ Whether the firing was an accident, homicide or suicide.

The nature of firearm

It is important to know whether the firearm used was a rifled weapon
or a smooth bore weapon, and if it was a rifled weapon, whether it
was a rifle, pistol, or revolver, (Table 4.). An examination of the size of
the bullet and its weight and calibre, the number, size, and direction of
the rifling marks on it, and the kind of metal it is made of, will all give
clues regarding the weapon used. For example, a bullet of 0.7 cm
diameter generally indicates that it has been fired from a weapon with a
calibre of 0.7 cm. The diameter of a bullet is measured with a
micrometer.

Table 4. Types of Firearms

Pistol is a miniature semi-automatic hand arm with a small barrel.

Revolver is a hand arm with a revolving cylinder filled with

cartridges.

Rifle is a rifled shoulder arm for long range firing. Effective range
may extend to a mile.

Submachine gun is an automatic rifled weapon, which also can be

used as a self-loading firearm.
 51

Light machine gun (LMG) is analogous to a rifle. It is of light

weight and is capable of rapid uninterrupted fire with accuracy.

Musket is a smooth-bore shoulder arm used for military purposes.

Shot gun is a smooth-bore shoulder arm used for hunting.

Air gun and Air rifle are suitable for small game hunting. Lead
slugs are used, the propelling force being obtained through
compressed of air.

Bullets may be recovered at the scene of a shooting incident, or from a

dead body during autopsy. Although a detailed examination of the bullet
recovered at autopsy is within the province only of a ballistics expert,
the medical officer conducting the autopsy should observe the
following points.

■ A bullet recovered from a dead body must not be washed or cleaned

as this may remove the residue of any powder adhering to it.
Instead, it should be dried without using heat and preserved for
future examination by a ballistics expert.

■ He must handle the bullet carefully. Forceps or other metallic

instruments must not be used in handling a bullet, for it will cause
not only artefacts such as scratches on it, but also obliterate the
existing rifling marks. Rubber-tipped forceps are best for handling
projectiles.

■ The size of the bullet, its weight, calibre, the number, size and
direction of rifling marks on it, the kind of metal of which it is
made, any blunting of its nose, and other relevant details should be
noted down. If the nose is blunted, it indicates that it had hit against
a hard object. When a lead bullet strikes a person wearing clothes,
the pattern of the weave of the clothing may sometimes be found
stamped on the nose of the bullet.
 52
■ The bullet is marked for future identification, by inscribing one's
initials on its base with a sharp pointed instrument, and not on its
sides or nose, as this will obliterate other marks that may already be
present.

■ Bullets meant for future examination must be wrapped in absorbent

cotton and preserved in empty cardboard boxes.

The suspect weapon and the crime bullet are both examined by a
ballistics expert. To find out whether the bullet recovered had been
fired from the suspect weapon, test firing is done. A test shot is fired
from the weapon into a box called firing box, which is packed with
cotton wool so that no distortion of the bullet occurs. The firing box is
open at the side from which firing is done, and also at the opposite
side. The bullet so fired (test bullet) is recovered. The test and crime
bullets are then compared under a comparison microscope. This is a
kind of microscope under which two objects can be compared
simultaneously. If the rifling marks are identical on the test and crime
bullets, the inference is that the suspect weapon was the weapon used
for the commission of the offence. The number, width, and depth of
rifling marks on a bullet can be accurately measured under a
mensuration microscope.

Examination of a spent cartridge case will also provide clues in

identifying the crime weapon. In the case of a shotgun cartridge, the
name of the manufacturing firm, and the calibre of the weapon for
which it is intended, are generally imprinted on the casing. Empty
cases of revolvers have a rim at their base, while those of pistols do
not.

The size of the spent case provides a clue regarding the calibre of the
weapon. In a revolver, the empty case usually remains within the
weapon, so that it is rare to find it at the scene of crime. If an empty
case is seen at the scene of crime, as in the case of a pistol or a rifle, it
is generally found a few feet to the right of the spot where the weapon
was discharged. The firing pin will make a dent on the base, which is
peculiar to that weapon. The breech may also leave its marks on it. The
 53
state of chemicals inside can assist in knowing whether it was recently
fired or not. All these points can help to identify a crime weapon. For
future identification, a spent case is marked by scratching one's
initials on its side.
In a shotgun wound, the nature of the shot, e.g., lead pellets, glass
beads, or stones, may help in identifying the weapon. Factory-made
shotgun cartridges use lead shot, while home-made ones employ glass
beads or stones. Lead pellets (and other kinds of shot), should be
wrapped in absorbent cotton, placed in an empty cardboard box and
preserved for examination.

Presence of wad at the scene of crime or in the dead body

conclusively indicates that a shotgun had been employed. The diameter
of the wad may give a clue regarding the calibre of the weapon. Wads
are preserved in an empty cardboard box for future examination.

Stains on the body of a victim can also provide help. Rifled weapons
employ cartridges with smokeless powder which does not cause
much blackening of the skin, because it burns up entirely, while the
black powder of shotguns causes extensive smudging.

The range of firing

The range of fire is deduced from the appearance of the entrance
wound (vide supra). However, an accurate range of firing is usually
better made out by test firing, than medical examination.

The direction of fire

If there is no deflection of the projectile, a line joining the entrance
wound with the exit wound in a dead body, or the area of lodgement
of the bullet will give the direction of fire. Cases of devious tracks, or
deflection of projectile due to hitting an intervening object (ricochet
bullet), can cause confusion in interpretation. An entry wound is
circular if the projectile enters perpendicular to body surface and oval if
entry is oblique. In the latter case, the edge on the side of the entry of
the bullet appears bevelled, while the opposite edge becomes
overhanging. In cases of oblique entry, the abrasion collar becomes
 54
eccentric, being wider at the side of entry (Fig. 9.8).

The site of firing

This will depend upon the calculation of range and direction of
firing.

Cause of death
Firearm injury can result in death due to haemorrhage, or damage to
any of the vital organs such as the heart or the brain.

Manner of death
It must be deduced as to whether a particular case of firearm death
was accidental, suicidal or homicidal. The important clues which can
help to resolve this are mentioned in Table 3
Table 9.3 Differences between Accidental, Suicidal, and Homicidal firearm
wounds

Feature Accidental Suicidal Homicidal

Site of entry wound Any part Head or chest Any part
Range Close Contact or close Any range
Direction Any direction Upward or Usually
backward upward
Number of One Usually one One or
wounds multiple
Firearm residue on Present Present Absent
hand
Weapon at the Present Present Usually
scene absent
Location Anywhere (usually Usually home Anywhere
home)
Sex Usually males Usually males Either sex
Motive Absent Depression, Robbery,
mental illness revenge, etc

The usual manner of death from firearms is either suicidal or

homicidal, while accidental deaths are less common. Suicides often
expose the site of election before shooting, as for example opening the
shirt before placing the muzzle over the chest They may also ensure
 55
that the muzzle is steady by holding the barrel by the non-firing hand,
which may thus sustain burns from flame. Accidental deaths are often
non-witnessed. However, firearm deaths almost always leave trace
evidence from the weapon in or about the victim's body, which can
be scientifically compared with the suspect weapon. In an accidental
case, examination of the weapon may reveal clues about accidental
discharge, such as defective safety catch, etc. Accidents usually occur
from careless handling of the gun, or unfamiliarity with operation
while cleaning, loading, or inspecting the firearm.

Box 1: Autopsy Procedure In Firearm Deaths

 Immediately after the dead body is received from the Police, an

attempt must be made to detect primer residue in both the
victim's hands (separately). Clean absorbent cotton buds or
cotton gauze dipped in rectified spirit can be used to mop the
hands. These are to be immediately transferred to clean glass
bottles containing rectified spirit. Alternatively, the hands can be
washed with rectified spirit, and the washings carefully collected
in clean bottles.

 Punctures» stains, etc., on the clothing of the dead body are to

be noted in detail, and subsequently photographed. The clothes
must then be carefully removed, dried in shade, and packed in
paper bags.

 External injuries on the body should be recorded carefully and

photographed. Entry wounds should be swabbed with absorbent
cotton soaked in rectified spirit, which are then transferred to
clean bottles containing rectified spirit.

 The dead body should be extensively X-rayed. Wet X-ray films

must preferably be examined before commencing dissection.
These films (after drying) should be marked with the following
identifying characteristics: autopsy number, serial number, date,
 56

site, side and nature of view, and preserved as permanent records

along with the autopsy report. X-rays are extremely helpful in
revealing the exact path of the projectile within the body.

 The planned routine autopsy should immediately follow. All

skin wounds as such should be dissected out carefully with
surrounding tissue (minimum 2.5cm thick). The dissected
wounds should be separately covered with absorbent cotton
soaked in rectified spirit, and placed in suitable glass containers
(containing rectified spirit). It is worthwhile to remember that
some entry wounds may be hidden or inconspicuous, and a
meticulous search of the entire body may be necessary to locate
them.

 A thorough search should be made to retrieve all bullets (in

rifled firearm death), or as many pellets as possible (in shotgun
death) from the corpse. Foreign particles from wounds, if
present, should be collected, placed in absorbent cotton, and
secured in clean and empty cardboard boxes.

 A bullet recovered from a dead body must not be washed or

cleaned, as this may remove the residue of any powder adhering
to it. Instead, it should be dried without using heat and
preserved. Bullets need to be handled carefully. Forceps or other
metallic instruments must not be used, for they will cause not
only artefacts such as scratches on it, which will interfere with
rifling marks, but may in fact totally obliterate the existing
rifling marks. Rubber tipped forceps are best for handling
projectiles. The size of the bullet, its weight, calibre, the number,
size, and direction of rifling marks on it, the kind of metal it is
made up of, any blunting of its nose, etc., as well as other
relevant details should be noted down. If the nose is blunted, it
indicates that it had hit against a hard object. When a lead bullet
strikes a person wearing clothes, the pattern of the weave of the
clothing may sometimes be found stamped on the nose of the
bullet.
 57
 The bullet is marked by one's initials on its base with a sharp
pointed instrument, to facilitate its subsequent identification in
court, and not on its sides or nose, as this will obliterate other
marks that may already be present. Bullets meant for future
examination must be wrapped in absorbent cotton and
preserved in empty cardboard boxes.

 Unfortunately, shotgun pellets cannot be traced to the

offending weapon by means of ballistic markings, as in the
case of bullets. However, a study of the wad used could help,
since the prints on the top-wad and its diameter can connect it
to the suspected weapon. The top-wad is almost always carried
into the body along with the shot.

 At the conclusion of the autopsy, all material objects thus

collected should be packed, labeled, tied, and sealed, and
forwarded to the ballistics expert through proper channel, along
with necessary forwarding notes, and samples of labels and
seal used.

 The medical opinion should include not only information about

the cause of death, but also (if possible) the kind of firearm
involved, and the range and direction of fire. Opinion about the
time of death, identity of the deceased, and the manner of death
may also be added if required.

Some other esoteric ballistic information is mentioned in Box 2

Box 2 Ballistic Trivia

 Dum-dum bullet—A type of bullet which is designed to

explode on impact.
 Incendiary bullet—A hollow-point bullet which contains
phosphorus.
 Frangible bullet—A bullet that is made of iron instead of
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lead, and fragments on impact.

Types of Lead Shot

 Dust shot— Consists of extremely fine particles.
 Bird shot— Consists of lead pellets of average diameter 3.5
mm. Used for small game hunting.
 Buck shot— Consists of large pellets of average diameter 6
to 8 mm. Used for big game hunting.

Unusual Ballistic Effects

 Billiard ball effect— Extensive dispersion of lead shot
because of the pellets striking against each other in flight.
May give erroneous impression about the range of fire.
 Balling of shot—The lead shot is bunched together for some
distance during flight, resulting In much less dispersion than
expected for that range.
 Tandem bullet—Sometimes, when a firearm is discharged,
the bullet does not emerge. On pulling the trigger again, two
bullets may emerge one behind the other. This happens in
faulty or disused firearms.
 Tandem (Duplex) cartridge—A single cartridge contains two
bullets one behind the other, so that a single shot produces
two separate entry wounds. Used in military rifles.
 Shored exit wound—if the skin at the exit wound is
supported against a wall, the wound may appear nearly
circular with a surrounding margin of abrasion, simulating
an entry wound.
 Yawing bullet—A bullet that has an unsteady trajectory
during flight.
 Tumbling bullet—A bullet that tumbles end-on-end
(somersaults) during flight
 Souvenir bullet—A bullet that remains in the body of a
surviving victim of gunshot injury for a long time without
producing any deleterious effects.
 Kennedy phenomenon—Surgical intervention and alteration
of a firearm wound, causing problems in medicolegal
 59
interpretation.

Methods of finding out whether a person recently discharged a

firearm:
 Harrison and Gilroy's test.
 Neutron activation analysis.
 Atomic absorption spectroscopy.

EXPLOSIVE INJURIES

Introduction
Catastrophic explosions of aircraft, railway trains, ships, and buildings,
firework mishaps, occupational or industrial fuel explosions, terrorist
bombings, and bombing due to wars, etc., have become commonplace
today in the international scenario. They result in mass disasters and
leave us not only mangled corpses, but also umpteen numbers of
injured victims requiring large-scale medical and surgical assistance.
Terrorist bombing sometimes involves dual explosions, wherein the
primary explosion is aimed at the target population, while a delayed
secondary explosion is aimed at the rescuers.

Classification
Explosive (blast) injuries are classified into four categories:
1. Primary blast injuries: They are due to the direct effect of "blast
overpressure." Injuries are caused by compressed air, which tends
to affect air-filled organs such as the lungs, gastrointestinal tract,
middle ear, etc.
2. Secondary blast injuries: They are caused by flying objects
generated by the blast.
3. Tertiary blast injuries: These injuries occur when victims are
thrown into the air and strike other objects.
4. Miscellaneous blast injuries: These comprise injuries from fire,
collapse of buildings, etc., which are the consequences of the
blast.

Mechanisms of death
Firework-related blast injuries cause a significant number of
 60
accidental morbidity and mortality in India, especially during the
festive season of Diwali.
Industrial accidents and explosions can trigger the release of toxic
agents or radioactive material, in addition to the blast effect. Terrorist
explosions may be of low or high intensity depending on the nature of
the organization and its resources. A minimum pressure of about 700
kilopascals (100 lb/sq inch) is needed for tissue damage in humans. In
most explosions, pulmonary contusion, pneumothorax and abdominal
injuries are the major reasons for mortality, while the middle ear is the
organ that is most susceptible to the primary blast. Pulmonary
barotrauma is the most common fatal primary blast injury. This term
encompasses pulmonary contusion, systemic air embolism, and free
radical-associated injuries such as thrombosis, lipoxygenation, and
disseminated intravascular coagulation. ARDS (acquired respiratory
distress syndrome) may be the result of direct lung injury, or shock
from other organ-system damage. Intestinal barotrauma is more
common in underwater blasts. Colon is usually the most affected).

Generally speaking, the intensity of an explosion declines as the cubed

root of the distance from the explosion. In other words, a person 3
meters from an explosion experiences 9 times more overpressure than a
person 6 meters away. Therefore, proximity of a person to the
explosion is an important factor in primary blast injury. Solid surfaces
reflect blast waves and increase the primary blast injury.

Flying debris, shards of glass, metal objects, etc., impart secondary

blast injuries, which can be lethal. They cause either blunt or
penetrating injuries. Some terrorists deliberately add metal screws and
nails to their explosives with the objective of enhancing lethality.
Tertiary blast injuries result from the victim flying through air and
hitting against walls, trees, poles, etc. Miscellaneous blast injuries
involving toxic inhalations, exposure to fire, toxins or radiations,
traumatic asphyxia, crush injuries, etc., add to the overall catastrophic
effect. Incomplete burning of plastic can release cyanides.

Abruptio placentae can result in a pregnant woman exposed to a blast,

when the pressure wave passes from a medium of high density
 61
(endometrium) to that of a medium of low density (placenta).

Medicolegal Significance
Most explosive deaths are either homicidal (due to terrorist activity),
or accidental. A few terrorist-related blasts may involve suicide
bombers. In India, the incidence of blast injuries is varied and sporadic.
States with terrorist problems report higher incidence, for e.g.,
Jammu & Kashmir. Also, blasts related to fireworks cause a
significant number of deaths in India, especially in Northern states
during the festival of Diwali. Careful autopsy and practical use of
laboratory rather than protocol tests are advisable in mass disasters.
Identification of the dead assumes great importance, and is
unfortunately extremely complex in large-scale explosions that cause
mass casualties with dismemberment or fragmentation. Blood tests for
carboxyhemoglobin, cyanides, and phosphorous may be necessary,
especially in closed-space explosions, or fire-related blasts.
Histopathology may help to detect ARDS, pulmonary contusion, or
myoglobinuric renal failure resulting from crush syndrome. Explosive
residues will have to be collected for subsequent examination by
experts in the field of explosives.

At the time of autopsy, the possibility of contamination of the body

with chemical or radioactive material should be kept in mind.