TRACE EVIDENCE

The term "trace evidence" is generally thought of as any type of evidence occurring in sizes so
small that it can be transferred or exchanged between two surfaces without being noticed.
A. HAIR
Hair is a thread-like structure that grows from hair follicles located in the skin of
mammals, including humans. It is made primarily of a protein called keratin, which is the
same protein found in nails and the outer layer of skin. Hair serves various functions, such as
providing protection, aiding in temperature regulation, and offering sensory information.
Hair has three main parts:
1. The Shaft: This is the visible part of the hair above the skin.
2. The Root: Located just below the surface of the skin, this part of the hair anchors it in the
follicle.
3. The Follicle: This is the structure in the skin from which hair grows. The follicle contains a
papilla, which supplies blood to the growing hair, and a matrix, where cells divide to
produce the hair shaft.
The Shaft:
It consists of three layers:
1. Cuticle: The outermost layer, made of overlapping cells that protect the inner
structure.
2. Cortex: The middle layer, containing pigment (melanin) that gives hair its color and
provides strength and flexibility.
3. Medulla: The central core, which can vary in structure and may be absent in fine
hair.
Hair color is primarily determined by the type, amount, and distribution of two types of
melanin pigments in the cortex layer of the hair shaft:
1. Eumelanin: Responsible for darker shades like black and brown.
2. Pheomelanin: Responsible for lighter shades like red and yellow.
• The combination and concentration of these two pigments result in the wide range of
natural hair colors seen in humans.
Types of Information Hair Provides
1. Identification of Species: Microscopic examination can determine whether a hair is
human or animal. Animal hairs have different structures, such as unique cuticle patterns
and medullary structures.
2. Racial and Ethnic Characteristics: Hair characteristics can sometimes indicate ethnic
origin (e.g., African, Asian, or European descent) based on morphology, like shape,
diameter, and pigment distribution.
3. Body Area Identification: Hair characteristics vary depending on the body area (e.g.,
head, beard, pubic). For instance, scalp hair is typically longer, finer, and has a more
uniform diameter, while pubic hair is shorter, coarser, and often curly.
4. Color, Length, and Chemical Treatment: The color and length of hair can match or
exclude suspects or victims. Chemical treatments like dyeing, bleaching, or perming alter
hair’s physical and chemical properties and can serve as distinguishing features.

What to Submit
Known head and pubic hair standards must be submitted from both subject(s) and
victim(s) for microscopic comparison. An appropriate known hair sample consists of a
minimum of 25 hairs collected randomly from a body area (head or pubic). These hairs
must include the root and should be dislodged by combing and then pulling if needed to
acquire the minimum number. Do not use forceps to pull hair. Samples from separate body
areas must be packaged separately in a sealed pharmaceutical fold or plastic bag and
labeled with at least the individual's name and area of body origin. Questioned and known
hair from sexual assault victims should be submitted as part of the sexual assault
evidence collection kit.
• When collecting hair samples from different parts of the body such as arms, armpits,
chest, legs and pubic area store separately according to location and mark each
receptacle with your initials, the date and exhibit number.
• Place inside the receptacle. If pillbox is used, take care that the length of the hair is
securely placed inside and not entangled by the lid. If paper is used as a receptacle, avoid
twisting the hair or fiber when folding the paper.
Hair Examination
1. Microscopic Examination
• Purpose: This analysis helps forensic scientists to determine basic characteristics of the
hair and potentially link it to a specific individual or group.
• Process:
• Under a microscope, analysts examine the morphological characteristics of the
hair, such as the cuticle pattern, cortex, medulla, color, diameter, and
condition (e.g., whether it has been dyed or damaged).
• These characteristics can help determine the species (human or animal), race, and
sometimes even the body area from which the hair originated.
• Limitations: Microscopic analysis alone cannot provide a conclusive link to a single
individual, as many people may share similar hair characteristics.
2. DNA Analysis
• Purpose: DNA analysis provides a more specific identification by analyzing the genetic
material found in the hair root or follicle.
• Process:
• Nuclear DNA can be extracted if the hair root is attached, which allows for a direct
match to a person’s genetic profile. This type of DNA is highly individual-specific.
• Mitochondrial DNA (mtDNA) can be analyzed from the hair shaft even if there’s
no root.
 • Limitations: DNA testing on hair requires either a hair root for nuclear DNA or an
intact hair shaft for mtDNA analysis. Mitochondrial DNA lacks the specificity of
nuclear DNA but can be useful when a root is not available.
B. FIBERS & THREADS
In such incidences as homicide, assault and sexual offenses involving personal contact and
struggle, fibers and threads can be inadvertently transferred between the clothing of a
suspect and victim. Fiber transfers can also occur between people and their environment (e.g.
carpeting, upholstery or bedding). A force of impact such as in the case of hit-and run, the
contact between the victim and the vehicle may result to fabric impressions, fibers, threads or
pieces of clothing left on the vehicle. An intruder entering a broken window may leave fibers
on the jagged glass or screen edges. Ropes and cordage from a crime scene can be compared
with known samples collected from a suspect.
Cases involving a struggle that has taken place require the submission of clothing from both
individuals. A note of caution: Do not handle the victim and suspect's clothing in the same
room to prevent cross contamination. Also, keep the victim's and suspect's clothing in
separate containers. At no time allow them to come in contact with each other. Do not
remove clothing after packaging to photograph or examine them.
Fibers from the victim's clothing may still be on the suspect's person for quite some time after
an incident. Submit the entire item to be examined. If attempting to collect fiber evidence in
the field, do not use alternate light since many fibers will not fluoresce under this type of light
and could be missed. If the entire item cannot be submitted, tape lift fiber from the source
and place in clean plastic surfaces for transport. Do not place tape lifts on paper or cards as
this may pose problems during recovery and comparison.
Fiber standards must be collected from known samples. All possible items from which the
victim and suspect could have obtained fiber transfer must be used as fiber standard. DO
NOT attempt to remove questioned fiber from clothing unless absolutely necessary to prevent
loss. Submit the entire item in a sealed paper bag.
Important Reminders
1. Fiber evidence are generally small in nature and thus must be protected from potential
loss.
2. Due to their microscopic nature, several methods must be resorted to in order to ensure
thorough collection such as: use of magnification tools, efficient alternate light sources.
3. Use recovery techniques that are least intrusive but practical such as picking, scraping or
vacuuming.
4. Wrap pieces of evidence to protect any adhering fibers from being lost.
5. Collect comparison standards from possible sources of fiber transfer.
6. All items must be sealed and labeled for identification.
Fiber Identification Methods
1. Physical Tests
a. Staining Test - Fibers will react differently when stained using chemical reagents. The
table below summarizes the behavior of different types fiber during the staining process.
b. Microscopic Examination. Microscopic examination will reveal the type of fiber since textile
fibers have different characteristics when seen under a microscope. This is the most
reliable and best means for identifying fiber.
2. Chemical Analysis
a. Burning Ignition Test. Fibers may be identified as to their origin whether they are animal,
vegetable or mineral by the characteristic smell emitted during burning. Also, the quality
of the burning and the appearance of the burnt end, color of ash and reaction to litmus
paper of the ash solution will reveal the type of fiber.
b. Solubility Test. This test is conducted by treating the fiber with certain chemicals. Fibers
behave differently in the presence of certain chemicals. Particular fibers may be dissolved
while others will not dissolve. This can be used as basis to identify types of fibers.
C. GLASS
Glass is often encountered as evidence in burglaries, homicides, assaults, and hit-and-run
offenses. Glass fragments easily embed in shoes and clothing of people involved in the
breakage of glass and its recovery can help investigators piece together a crime. One can tell
whether pieces of glass recovered from the crime scene and from the person of the suspect
belong to the same class or not.
Direction of force can be determined from the pattern of glass breakage. The determination of
the ‘direction force’ is helpful information whether glass was broken from inside of from the
outside. When information regarding the direction of force is needed, all broken glass must be
recovered and submitted for analysis. Leave the remaining glass in the window or doorframe
intact and mark as to exterior and interior surfaces.
• Radial Cracks: These cracks radiate outward from the point of impact. They are the first
fractures to form and indicate the general direction of the force. Radial cracks form on the
side of the glass opposite the impact.
• Concentric Cracks: These are circular or semi-circular cracks that form later, typically
around the impact point. They indicate secondary stresses.
Obtain all glass evidence found in the possession of the suspect or fractures left on the scene.
Submit all clothing worn by the suspect for possible glass fractures embedded. Do not
attempt to remove glass from clothing unless absolutely necessary for its preservation. Glass
standards should be submitted for comparison purposes. The comparison glass standard
should always be taken from any remaining glass in the window, or doorframe or headlight, or
as close as possible to the point of breakage.
Collection of Glass Evidence
• For broken windows, collect from all four corners of the broken window. If this is not the
case, collect all the glass that is available.
• If more than one type of glass is broken, collect representative samples of each type.
• Use appropriate containers for keeping glass samples. For small shards, round pillboxes
are the best containers.
• Glass can get lodged in the hair and clothing or persons. If clothing is to be submitted,
allow it to dry first and then package in individual paper bags. The soles of shoes
frequently pick up glass fragments and can be submitted also as evidence.
• For purposes of reconstruction, collect all the glass possible and carefully package to
prevent further breakage.
• Direction of force is best determined at the scene from pieces of glass still in the frame.
Once removed from the scene, the laboratory cannot make such a determination from a
single piece. So remove as much glass as possible from the frame and mark said pieces to
indicate which is inside or outside before they are submitted to the laboratory.
Information Determined from Glass Evidence
• Whether questioned fragments have originated or not from a particular source.
• What side of the glass was forced applied?
• Whether broken fragments belong to a single piece.
• Determination of class characteristics such as: refractive indices, elemental composition,
densities.
• Actual identification if a reconstruction would fit the pieces of glass like a jigsaw puzzle.
• For broken windows caused by a fired bullet, it is possible to determine the bullet’s
direction by noting the pattern of breakage on the cone-shaped hole left by the bullet. The
small opening is the entrance side while the large opening is the exit side of the bullet.
• For several bullet holes, the sequence by which the bullet holes were caused can be
determined by noting the radial fractures. Radial fractures caused by the passage of a
bullet will stop at any pre-existing fracture.
D. PAINTS AND COATINGS
Paint can easily be transferred by contact with painted surfaces especially when there is
forceful contact. In hit-and-run cases, the impact of the car on the victim can potentially
transfer paint from the car to the skin of the victim. Force applied by tools of a burglar can
pick up paint and adhere to the tool for some time. Paint chips or scrapings can also be
transferred to the clothing of victims especially for loose or wet paint.
HIT-AND-RUN VEHICLE
It is possible to match physically paint that is left at the scene back to a suspect's vehicle. No
paint should be removed from the damaged areas of the vehicle. As much as possible, the
entire suspect vehicle should be submitted to the laboratory for processing. If this is not
possible, paint should be taken from the damaged area/panel of the vehicle using a clean,
unused blade for each area and packaged separately. Known standard samples should be
collected from the original undamaged paint within one inch of each damaged area and also
packaged separately. Package in separate pharmaceutical folds, seal and label accordingly.
Never use adhesive tape to collect paint samples.
NOTE: Time is critical in hit-and-run cases requiring investigative lead information. Submit
evidence from hit-and-run victims as soon as practical.
Collection of Paint Evidence
1. Use a clean unused blade to obtain paint samples from locations of damage in a vehicle.
2. Collect samples in such as manner as to obtain paint sample from all layers of paint
present. If it is possible to remove the item from the vehicle, do so and let the laboratory
remove the paint.
3. Collected paint sample must be placed on clean white paper and folded into a
pharmaceutical fold. Seal, label and place in an envelope or plastic bag. Do not use tape to
transfer or pick up paint samples.
4. For paint adhering to clothing, do not attempt to remove. Submit the whole piece of
evidence to the laboratory. If clothing is wet, dry on clean white paper taking precaution not
to lose adhering microscopic evidence. When dried, package clothing in paper bags. Do not
use plastic bags.
5. Treat garments individually by placing each garment in a separate bag.
6. Tools used to gain entry can pick up traces of paint in the process. If such transfers may be
present, ensure that this evidence is not lost by enclosing the end of the tool in a plastic or
paper bag and secure with tape. It is preferable that the entire tool or object is submitted for
microscopic examination. DO NOT remove paint by scraping the surface. Tools may also
deposit paint onto the surface it is in contact with. Submit also the marked or indented area
for trace evidence examination before casts or impressions are made of the tool marks.
7. When practicable, submit entire objects or cut out areas that bear paint smears and
transfers to the laboratory for processing.
8. Keep each sample collected in a separate sealed container and label accordingly.
E. PLASTICS AND POLYMERS
Plastics are used in a wide variety of modern products such as vehicle parts, decorative trim
tapes, decals, adhesive tapes (duct, electrical, masking, etc.) or rubber. In the course of a
crime, these may be broken or transferred from one source to another and can direct
investigators to pursue leads to a crime.
Collection and Submission of Plastic Evidence
All plastic evidence must be submitted to the laboratory in an appropriately sealed and
labeled condition. The same collection and packaging procedures outlined for paint evidence
should be used for plastic evidence.
When vehicle parts are recovered from a hit-and-run scene, investigators should try to have
these identified by auto dismantlers or vehicle parts employees or retailers. These may also
be submitted to the laboratory for examination.
E. Paper & Inks
Paper and Ink come into the province of forensic chemistry when questioned documents
become the subject of investigation. The essential materials in a document examination of
any kind are the paper and ink or pencil or writings. Examination of the paper will reveal the
type of paper used, the age of the document, alterations or erasures and other forms of
forgery that may be present in the subject document. Examination of the ink, on the other
hand can reveal such information as: whether two writings were made with the same ink, or
inks in different conditions. It can also reveal whether there are continuous writings at one
time under the same conditions or whether erasures have been made and superimpositions
have been made.
Collection and Submission of Evidence
Questioned documents should be submitted to the laboratory in an appropriately sealed and
labeled evidence container. Samples, if wet, must be air dried before they are packed.
Packaging must be done to ensure that the evidence is not subjected to humidity changes
that may cause ink to smudge and soil.
 F. SOIL
Soil is frequently found on clothing, shoes, or tools and in the wheel wells of vehicles.
Information Determined
Most soil analysis consists of comparing two or more samples by their mineral content, color,
and density. The presence of pesticides and herbicides have also been used in soil
comparison.

Collection of Soil Evidence

1. Clothing or shoes should be dried and then placed in individual paper bags.
2. Known soil samples should be collected as follows:
a) One sample at the point of suspected origin;
b) One sample on each side about one foot away
c) One sample on each side about 10 feet way.
These samples should be taken from approximately the same depth as the questions sample. If a
shoe print is one quarter of an inch deep, do not sample an inch or more in depth. The zip-lock
plastic bags in the trace kit are convenient for such a sample. A bag about half-full of soil would
provide an adequate sample.

G. Impression Evidence
Impression Evidence are referred to as tool marks. These can be anything from cuts,
scratches, gouges, abrasions that are left by tool when it comes in contact with a surface with
relative force applied.
a) Negative Impression. When a tool is pressed against or into a surface such as when a
crowbar is used to try to open a door or window or a hammer is pounded against a wall, a
mark us usually left. The mark that is left on the surface is referred to as a negative
impression.
b) b) Abrasion or Friction. Mark is made when a tool cuts into or slides across a surface.
This type of mark may be made by a pair of pliers, a bolt cutter, knife, ax, saw, drill, plane,
or a die used in the manufacture of wire.
c) c) Combination mark. When both a negative impression and a friction or abrasion mark
are left on surfaces these are referred to as combination marks.
Information Determined
These are usually discovered on doors, windows, window panes and other openings when
force is applied using tools in the attempt to forcibly enter or exit. When searching the crime
scene, investigators must be alert to search in the immediate scene and its vicinity for tools
that may have been used.
In many instances, footwear impressions can be used to identify brands of shoes and tie this
to the identify criminals. And tire impressions can be positively identified as having been
made by a certain type of tire. These can give valuable information that can help provide
investigative leads towards the successful solution of a crime.
Ideally, the whole object containing the tool marks must be submitted to the laboratory
instead of just the area containing the mark. In certain instances, this may not be possible in
which case the impression must be carefully photographed and sketch made of the area
containing the mark.
Uses of Tool Mark Evidence
1. Can link a person to a crime if ownership of a certain tool is narrowed down to that person
alone.
2. To establish if any tool found at the crime scene is material to the crime being investigated
or whether it has no connection with the crime.
3. May be used to see any connection between similar evidences found in other crime
scenes.
4. Will help investigators determine from where an opening was forcefully pried.
5. Tool marks serve as comparison models to be matched from those in the crime scene to
those found in the possession or within the territory of the suspect.
6. It narrows to search to a given tool or weapon.
7. Cast of tool marks to be of any value is an investigation have to be carefully and properly
crafted. Poor casts are not only useless but can also ruin the negative impressions that are
being developed.
H. Fractured Materials (Physical Matches)
It is possible to examine any broken, torn, cut or separated items to determine whether or not
they were at one time a single, intact item. This type of examination can determine if
evidence did originate from one particular source.
Pieces collected from different location must be packaged separately, taking care to avoid
any further damage to the fractured surfaces.
Every attempt should be made to submit all the pieces of the broken item.
Care must be taken not to cross contaminate broken items that may have other types of trace
evidence on them.
I. General Materials
This class of materials may include such materials as fire extinguisher residue, metals,
cosmetics and building materials. This list is not all-inclusive, but will include all other
materials not expressly discussed above. Examinations are limited to identification or
classification of the material, and not a comparison with suspected sources of origin. If the
evidence is of a type never encountered before, a method for its analysis must be developed.