Forensic Science

Unit 3 : Evidences: Collection, Preservation and Packaging

Types of Evidences
 Direct Evidence:
 This type of evidence directly proves a fact without requiring any inference or
interpretation. It can be a firsthand account of an event.
 Examples: Eyewitness testimony, video footage of a crime, a murder weapon with
the suspect's fingerprints.
 Circumstantial Evidence:
 Circumstantial evidence doesn't directly prove a fact but rather provides indirect
information that, when combined with other evidence, can lead to a conclusion.
 Examples: Footprints near a crime scene, a suspect's presence near the scene, or a
motive that implies guilt.
Types of Evidences

 Physical Evidence:
 Physical evidence includes tangible objects or items that can be presented in court
to establish facts or support claims.
 Examples: Weapons, clothing, drugs, fingerprints, hair, fibers, and DNA.
 Documentary Evidence:
 This type of evidence consists of written or printed documents that provide
information relevant to a case.
 Examples: Contracts, emails, letters, deeds, medical records, and financial
documents.
Types of Evidences
 Testimonial Evidence:
 Testimonial evidence comprises statements made by witnesses or individuals under
oath during legal proceedings.
 Examples: Witness testimony, confessions, and expert witness opinions.
 Demonstrative Evidence:
 Demonstrative evidence is used to help explain or illustrate facts to the jury or
judge and can include visual aids, diagrams, or models.
 Examples: Maps, diagrams, charts, photographs, and models.
Types of Evidences
 Trace Evidence:
 Trace evidence refers to small pieces of physical evidence that can be transferred
between objects or persons during contact.
 Examples: Hair, fibers, paint chips, soil, glass fragments, and gunshot residue.
 Biological Evidence:
 Biological evidence is derived from living organisms or their remains and is often
crucial in forensic investigations.
 Examples: Blood, saliva, semen, tissue samples, bones, and DNA
Types of Evidences

 Digital Evidence:
 Digital evidence is information stored or transmitted in digital format, frequently
related to computer or electronic devices.
 Examples: Emails, text messages, computer files, surveillance video footage, and
GPS data.
 Real Evidence:
 Real evidence consists of tangible objects or physical items that played a direct
role in the commission of a crime.
 Examples: The murder weapon, stolen property, or a broken lock.
Types of Evidences
 Character Evidence:
 Character evidence pertains to a person's character, reputation, or traits and can
be used to establish a person's credibility.
 Examples: Testimonies about a person's honesty, integrity, or past behavior.
 Expert Evidence:
 Expert evidence involves testimony or opinions provided by qualified experts in a
specific field to help the court understand complex issues.
 Examples: Forensic experts, medical professionals, and forensic accountants
offering their expertise.
Collection and Packaging Physical Evidence
 Step 1: Safety Precautions
 Ensure safety by wearing personal protective equipment like gloves and, if necessary, masks.
 Secure the crime scene to prevent unauthorized access.
 Step 2: Documentation
 Document the location, condition, and context of the evidence at the crime scene.
 Take detailed notes, photographs, and sketches to record the evidence's position.
 Step 3: Selection of Tools
 Choose the appropriate tools for collecting specific types of evidence, such as:
 Tweezers or forceps for delicate items.
 Swabs or collection kits for biological evidence.
 Evidence bags, envelopes, or containers for various items.
Collection and Packaging Physical Evidence
 Step 4: Chain of Custody
 Establish a chain of custody record for each piece of evidence.
 Record who collects, handles, and transfers the evidence, along with dates and
times.
 Step 5: Collection of Biological Evidence
 For biological evidence like blood, saliva, semen, or tissues:
 Use sterile swabs, collection kits, or containers.
 Allow evidence to air dry before packaging to prevent mold growth.
Collection and Packaging Physical Evidence

 Step 6: Collection of Trace Evidence

 For trace evidence like hair, fibers, glass, or gunshot residue:
 Use forceps, tweezers, or adhesive tape.
 Collect items individually and place them in separate containers or envelopes.
 Step 7: Handling Firearms and Weapons
 Handle firearms and weapons with care to prevent accidental discharge.
 Ensure safety mechanisms are engaged:
 Unload firearms.
 Safely secure ammunition.
 Package firearms and ammunition separately and securely.
Collection and Packaging Physical Evidence

 Step 8: Fingerprint Collection

 Dust for latent fingerprints using fingerprint powder.
 Lift fingerprints using adhesive tape or specialized lifting materials.
 Place lifted prints on fingerprint cards or transparent backing sheets.
 Step 9: Arson Evidence Collection
 For arson evidence, collect samples from the fire scene using clean, airtight containers.
 Seal containers to preserve volatile substances like accelerants.
 Step 10: Drugs and Narcotics Collection
 Package drugs or narcotics in airtight containers or evidence bags.
 Label containers with details like the type of substance, quantity, and location of recovery.
Collection and Packaging Physical Evidence

 Step 11: Collection of Biological Fluids

 Use clean, sterile containers to collect and store bodily fluids like urine, vomit, or sputum.
 Seal containers to prevent leakage.
 Step 12: Firearms and Ballistics Collection
 Package firearms, casings, and bullets separately in secure containers.
 Ensure firearms are unloaded and safeties are engaged.
 Step 13: Toolmarks and Impressions Collection
 Use casting materials to create impressions of toolmarks or tire treads.
 Label and protect the casts to prevent damage.
Collection and Packaging Physical Evidence

 Step 14: Packaging

 Select appropriate packaging materials for each type of evidence, such as:
 Paper bags for items that need to breathe (e.g., clothing).
 Envelopes for small items (e.g., shell casings).
 Boxes for larger items (e.g., weapons).

 Seal packaging with evidence tape, ensuring it's properly labeled with case details.
 Step 15: Labeling
 Clearly label each package with information including the case number, item description,
date, collector's name, and chain of custody details.
Collection and Packaging Physical Evidence

 Step 16: Preservation

 Store evidence in a secure, climate-controlled facility to prevent degradation.
 Maintain a log of evidence storage conditions and access.
 Step 17: Submission
 Follow proper procedures for submitting evidence to a forensic laboratory for analysis.
 Complete evidence submission forms accurately and comprehensively.
 By following these step-by-step guidelines, investigators can collect and package
physical evidence effectively, preserving its integrity and ensuring its reliability
throughout the investigative and legal process.
 Collecting Physical Evidence
 Collecting physical evidence is a crucial aspect of forensic investigations, as it provides
tangible proof of events and plays a vital role in solving crimes.
 Secure the Crime Scene
 Wear Protective Gear
 Document the Scene
 Establish Chain of Custody
 Identify and Prioritize Evidence
 Use Proper Collection Tools
 Collect Biological Evidence
 Collect Trace Evidence
 Handle Firearms and Weapons
 Collect Fingerprint Evidence:
Collecting Physical Evidence

 Collect Arson Evidence

 Package Evidence Properly
 Labeling
 Preserve Evidence
 Submit to the Laboratory
Collecting Physical Evidence

 Secure the Crime Scene:

 Before collecting evidence, ensure the safety and security of the crime scene.
 Restrict access to authorized personnel to prevent contamination or tampering.
 Wear Protective Gear:
 Put on appropriate personal protective equipment (PPE), such as gloves and, if
necessary, masks, to avoid contaminating the evidence.
 Document the Scene:
 Thoroughly document the crime scene by taking photographs, making sketches,
and writing detailed notes.
 Capture the overall scene, close-up shots of evidence, and any relevant details.
Collecting Physical Evidence
 Establish Chain of Custody:
 Create and maintain a chain of custody record for each piece of evidence collected.
 Document who collects, handles, and transfers the evidence, along with dates and times.
 Identify and Prioritize Evidence:
 Identify potential evidence by visually inspecting the scene.
 Prioritize the collection of fragile or perishable evidence that may degrade over time.
 Use Proper Collection Tools:
 Select appropriate tools based on the type of evidence:
 Tweezers or forceps for delicate items.
 Swabs or collection kits for biological evidence.
 Evidence bags, envelopes, or containers for various items.
Collecting Physical Evidence

 Collect Biological Evidence:

 For biological evidence like blood, saliva, or hair:
 Use sterile swabs or collection kits.
 Air dry the evidence before packaging to prevent mold growth.
 Collect Trace Evidence:
 For trace evidence like fibers, glass, or gunshot residue:
 Use forceps, tweezers, or adhesive tape.
 Collect items individually and place them in separate containers to prevent cross-
contamination.
Collecting Physical Evidence

 Handle Firearms and Weapons:

 Exercise extreme caution when handling firearms and weapons to avoid accidental
discharge.
 Ensure safety mechanisms are engaged and the weapon is unloaded.
 Package firearms and ammunition separately in secure containers.
 Collect Fingerprint Evidence:
 Dust for latent fingerprints using fingerprint powder.
 Lift fingerprints using adhesive tape or specialized lifting materials.
 Place lifted prints on fingerprint cards or transparent backing sheets.
Collecting Physical Evidence

 Collect Arson Evidence:

 For arson evidence, collect samples from the fire scene using clean, airtight
containers.
 Seal containers to preserve volatile substances like accelerants.
 Package Evidence Properly:
 Choose appropriate packaging materials based on the type of evidence:
 Paper bags for items that need to breathe (e.g., clothing).
 Envelopes for small items (e.g., shell casings).
 Boxes for larger items (e.g., weapons).
 Seal packaging with evidence tape, ensuring it's properly labeled with case details.
Collecting Physical Evidence

 Labeling:
 Clearly label each package with information, including the case number, item
description, date, collector's name, and chain of custody details.
 Preserve Evidence:
 Store evidence in a secure, climate-controlled facility to prevent degradation or
contamination.
 Maintain a detailed log of evidence storage conditions and access.
 Properly collecting and preserving physical evidence is essential for
maintaining its integrity and ensuring its admissibility in legal proceedings.
 Handling Evidence
 Handling evidence is a critical aspect of forensic investigations and legal proceedings.
Proper handling ensures the preservation of evidence integrity and its admissibility in
court. Here are guidelines for handling evidence:
 Wear Personal Protective Equipment (PPE):
 Always wear appropriate PPE, such as gloves and masks, when handling evidence to prevent
contamination.
 Avoid Contamination:
 Minimize contact with evidence to prevent contamination.
 Use clean tools and gloves when handling items.
 Document Chain of Custody:
 Maintain a clear and detailed chain of custody record for each piece of evidence.
 Document who collected, handled, and transferred the evidence, along with dates and
times.
Handling Evidence
 Use Proper Tools:
 Select the appropriate tools for handling specific types of evidence.
 Tweezers, forceps, and swabs are common tools used in evidence handling.
 Package and Label:
 Package evidence in suitable containers or bags to preserve its integrity.
 Seal packages with evidence tape and label them with relevant information, including
the case number, item description, date, collector's name, and chain of custody details.
 Maintain a Secure Storage Environment:
 Store evidence in a secure, controlled environment to prevent degradation or
tampering.
 Maintain proper temperature and humidity conditions.
Handling Evidence
 Prevent Damage:
 Handle evidence carefully to avoid damage.
 Use appropriate techniques when lifting fingerprints or collecting trace evidence.
 Avoid Alteration:
 Do not alter or manipulate evidence in any way that could compromise its integrity or
authenticity.
 Avoid unnecessary handling.
 Document Handling Procedures:
 Keep records of all actions taken when handling evidence, including when and how it
was collected, packaged, and stored.
 Follow Legal and Ethical Guidelines:
 Adhere to legal and ethical guidelines when handling evidence, ensuring it is collected
in a manner that respects individuals' rights and privacy.
Handling Evidence

 Use Preservation Techniques:

 Employ preservation techniques to prevent evidence from deteriorating over time,
especially in the case of biological or chemical evidence.
 Maintain a Secure Chain of Custody:
 Ensure that evidence is always in the possession of authorized individuals.
 Record all transfers of custody accurately.
 Ensure Proper Documentation:
 Maintain complete and accurate records of evidence handling, including
photographs, notes, and sketches.
 Seek Expert Assistance:
 Consult with forensic experts or specialists when dealing with complex or
specialized evidence types.
Handling Evidence

 Adhere to Laboratory Protocols:

 If evidence is sent to a forensic laboratory, follow their protocols for submission
and handling.
 Testify Truthfully:
 If required, testify truthfully about the handling and preservation of evidence
during legal proceedings.
 Follow Jurisdictional Requirements:
 Comply with the specific legal and procedural requirements of your jurisdiction
regarding evidence handling.
Packaging Evidence
 Properly packaging evidence is essential to maintain its integrity, prevent
contamination, and ensure its admissibility in court. Here are step-by-step
instructions on how to package evidence effectively:
 Select Appropriate Packaging Materials:
 Choose the appropriate packaging materials based on the type and size of the evidence.
 Common packaging materials include evidence bags, envelopes, boxes, or containers.
 Wear Personal Protective Equipment (PPE):
 Before handling evidence, put on personal protective equipment (PPE) like gloves to avoid
contaminating the evidence.
Packaging Evidence

 Label and Document:

 Clearly label the packaging with the following information:
 Case number: A unique identifier for the specific case.
 Item description: A brief description of the evidence.
 Date and time: When the evidence is packaged.
 Collector's name: The name of the person packaging the evidence.
 Chain of custody details: Record the transfer of custody, including names, dates,
and times.
 Use Evidence Tape:
 Seal the packaging with evidence tape, which is tamper-evident and provides
a clear indication if the package has been opened.
Packaging Evidence
 Prevent Cross-Contamination:
 If there are multiple pieces of evidence, package them separately to prevent cross-
contamination.
 Use separate packaging for each item or ensure they are individually sealed within
a larger container.
 Consider Breathable Packaging:
 For evidence that may retain moisture, such as clothing or biological samples, use
breathable packaging like paper bags. This helps prevent the growth of mold or
deterioration.
 Document the Packaging Process:
 Keep detailed records of the packaging process, including photographs if
applicable.
 Document the condition of the evidence before and after packaging.
Packaging Evidence
 Protect Fragile Evidence:
 Fragile items, such as glass or delicate objects, should be packaged with extra
care. Use padded or cushioned materials to prevent breakage.
 Maintain the Chain of Custody:
 Ensure that the chain of custody is maintained throughout the packaging process.
 Record any transfers of custody and the individuals involved.
 Store Securely:
 Store the packaged evidence in a secure, controlled environment, such as an
evidence room, to prevent tampering or contamination.
Packaging Evidence

 Follow Jurisdictional Procedures:

 Familiarize yourself with the specific procedures and regulations of your
jurisdiction regarding evidence packaging and storage.
 Submit to the Laboratory:
 If the evidence is to be sent to a forensic laboratory for analysis, follow their
specific submission protocols, including packaging requirements.
 Maintain Records:
 Keep comprehensive records of the packaging and submission of evidence, as this
documentation is crucial for legal proceedings.
Conducting a Methodical Search of Evidence

 Conducting a Methodical Search of Evidence

 Search Patterns
 Strip or Line Search
 Grid Search
 Spiral Search Method
 Wheel/Ray Search
 Quadrant or Zone Search
Conducting a Methodical Search of Evidence
 Strip or Line Search:
 In a strip or line search, investigators walk in a straight line from one end of the
crime scene to the other.
 This method is efficient for covering large, open areas, but it may miss smaller
items between the search lines.
Conducting a Methodical Search of Evidence
 Grid Search:
 A grid search involves dividing the crime scene into a grid by creating
perpendicular lines.
 Investigators systematically search each square of the grid, ensuring thorough
coverage.
 It's a methodical approach suitable for both large and small crime scenes.
Conducting a Methodical Search of Evidence
 Spiral Search Method:
 The spiral search method begins at the center of the crime scene and spirals
outward.
 Investigators continue in a circular pattern, working their way to the outer edges.
 This pattern is useful for locating a central point of interest or when dealing with a
circular crime scene.
Conducting a Methodical Search of Evidence
 Wheel/Ray Search:
 In a wheel or ray search, investigators start from a central point and radiate
outward, like spokes of a wheel.
 This pattern is efficient for locating items originating from a central point, such as
evidence ejected from a vehicle crash.
Conducting a Methodical Search of Evidence
 Quadrant or Zone Search:
 Divide the crime scene into quadrants or zones, assigning specific areas to search
teams or individuals.
 Each team thoroughly searches their assigned area, ensuring that no part of the
scene is left unexamined.
 Quadrant or zone searches are suitable for complex or large crime scenes.
Biological Materials

 Biological materials, in the context of forensic science and criminal

investigations, refer to any substances or samples that originate from living
organisms. These materials are often valuable sources of evidence in criminal
cases because they can link individuals to a crime scene, victims, or each
other. Here are some common types of biological materials encountered in
forensic investigations:

 Blood:
 Blood is a vital biological material commonly found at crime scenes.
 It can be used to identify individuals through DNA analysis, determine blood type,
and assess the presence of drugs or toxins.
Biological Materials

 Saliva:
 Saliva may contain DNA that can be used for identification purposes.
 It can also be tested for the presence of drugs or toxins.
 Semen:
 Semen is a biological material crucial in sexual assault cases.
 DNA analysis of semen can link a suspect to a victim or crime scene.
 Hair:
 Hair samples can be analyzed for DNA, which may provide information about an
individual's identity.
 Hair evidence can also reveal details about its source, such as species or origin.
Biological Materials

 Skin Cells:
 Shed skin cells, also known as epithelial cells, can be found on objects touched by
individuals.
 DNA analysis of skin cell samples can link a person to an object or location.
 Tissues and Organs:
 Biological tissues and organs, whether living or postmortem, can yield valuable
information.
 Autopsy examinations of tissues and organs can provide insights into the cause of
death or injury.
Biological Materials

 Bone:
 Bones may be encountered in various forensic contexts, including crime scenes and
archaeological investigations.
 DNA analysis of bone fragments can help identify individuals.
 Urine:
 Urine can be tested for the presence of drugs, alcohol, or toxins.
 It may also be used for genetic testing in some cases.
 Vomit:
 Vomit can contain traces of substances ingested by an individual.
 It may be analyzed to determine the presence of drugs or toxins.
Biological Materials

 Feces:
 Fecal samples can contain evidence of ingested substances, pathogens, or toxins. -
In some cases, they may be tested for DNA.
 Tears:
 Tears may be examined for the presence of chemicals or substances, particularly
in cases of poisoning.
 Breast Milk:
 Breast milk can be tested for drugs or toxins when relevant to a case, such as child
endangerment.
Biological Materials

 Body Fluids from Decomposition:

 Decomposing bodies release various fluids, such as putrefaction fluid and
postmortem fluids.
 These fluids can provide information about the postmortem interval and cause of
death.
 Forensic scientists use various techniques, including DNA analysis, serology,
and toxicology, to analyze biological materials for investigative and
evidentiary purposes. Proper collection, preservation, and analysis of these
materials can play a crucial role in solving crimes and providing justice in
legal proceedings.
Collection, Preservation, Packaging…

 Collecting, preserving, and packaging various types of forensic evidence, such

as bloodstains, hair, dust, petroleum products, drugs and poisons, DNA,
firearms, toolmarks, and other impressions, requires specific techniques and
materials. Here's a general guide on how to handle these different types of
evidence:
Collection, Preservation, Packaging…

Bloodstains
 Collection:
 Use a sterile swab or gauze to collect small bloodstains or blood spatters.
 For larger stains, cut out a portion of the fabric or material containing the stain.
 Preservation:
 Allow swabs or fabric samples to air dry before packaging.
 Seal items in a clean, breathable paper bag or envelope.
 Packaging:
 Label the packaging with the case number, description of the evidence, date, and
collector's name.
Collection, Preservation, Packaging…

Hair
 Collection:
 Use clean, sterile tweezers or forceps to pluck individual hairs.
 Collect hairs with their roots intact for DNA analysis.
 Preservation:
 Place collected hairs in a clean, dry envelope or small container.
 Avoid excessive handling to prevent contamination.
 Packaging:
 Label the packaging with relevant information and the collector's name.
Collection, Preservation, Packaging…

Dust and Trace Evidence

 Collection:
 Use adhesive tape, sticky lint rollers, or specialized brushes to collect dust and
trace particles.
 Carefully lift particles from surfaces or objects.
 Preservation:
 Place collected particles on clean glass slides or in small envelopes.
 Avoid touching or contaminating the samples.
 Packaging:
 Label the packaging with case details and the collector's name.
 Seal envelopes or containers to prevent contamination.
Collection, Preservation, Packaging…

Petroleum Products
 Collection:
 Use clean containers or bottles to collect liquid petroleum products.
 Use clean tools to scrape or collect solid or semi-solid substances.
 Preservation:
 Ensure that containers are tightly sealed to prevent evaporation or contamination.
 Packaging:
 Label the containers with case details, the type of petroleum product, and the
collector's name.
Collection, Preservation, Packaging…

Drugs and Poisons

 Collection:
 Use clean tools to collect suspected drugs or poisons.
 Place solid substances in clean containers or envelopes.
 For liquids, use airtight containers.
 Preservation:
 Ensure that containers are tightly sealed to prevent contamination.
 Maintain a chain of custody.
 Packaging:
 Label containers with case details, type of substance, quantity, and collector's
name.
Collection, Preservation, Packaging…

DNA
 Collection:
 Use sterile swabs or collection kits to collect biological samples containing DNA.
 Preservation:
 Air dry swabs or samples thoroughly.
 Seal them in airtight containers or envelopes to prevent contamination.
 Packaging:
 Label containers with case details, sample type, and collector's name.
 Collection, Preservation, Packaging…

Firearms
 Collection:
 Ensure firearms are safe (unloaded with safety mechanisms engaged) before
handling.
 Place firearms in a firearm box or evidence bag.
 Preservation:
 Secure firearms to prevent tampering or discharge.
 Packaging:
 Label the packaging with case details and firearm information.
Collection, Preservation, Packaging…

Tool Marks and Other Impressions

 Collection:
 Use casting materials to create impressions of toolmarks or tire treads.
 Photograph the impressions before collecting.
 Preservation:
 Allow casts or impressions to harden and dry completely.
 Packaging:
 Label casts or impressions with case details, type of impression, and collector's
name.
Chain of Custody

 What Is It?
The chain of custody is a chronological record of the individuals who have
had control, possession, or access to physical evidence during an
investigation.
 Why Is It Important?
It ensures the integrity and reliability of evidence in legal proceedings.
It provides a documented history of how evidence was handled, preventing
tampering or contamination.
 Chain of Custody
 Key Elements
 Identification: Each piece of evidence is identified with a unique case number or identifier.
 Documentation: Detailed records are kept at every stage of the evidence's journey, including
when it was collected, transferred, received, analyzed, and stored.
 Signatures: The names and signatures of all individuals who handle the evidence are
recorded.
 Starting Point
 The chain of custody begins when evidence is collected at the crime scene. The collector
must:
 Properly package and label the evidence.
 Document the date, time, and location of collection.
 Sign and date the documentation.
 Chain of Custody

 Transfers
 Whenever evidence changes hands, a transfer is recorded.
 Both the person transferring the evidence and the recipient sign and date to acknowledge
the transfer.
 This includes transfers between investigators, forensic analysts, or storage facilities.
 Storage and Handling
 Evidence is stored in secure, controlled environments to prevent contamination,
tampering, or degradation.
 Storage locations are documented, and access is restricted to authorized personnel.
Chain of Custody

 Analysis
 Forensic experts or analysts document their interactions with the evidence, including:
 The date and time of analysis.
 Techniques and methods used.
 Results of the analysis.

 Court Presentation
 In a legal proceeding, the custodian of the evidence testifies about its handling and the
integrity of the chain of custody.
 This testimony is crucial for establishing the credibility and reliability of the evidence.
Chain of Custody

 Chain Breaks
 If at any point the chain of custody is compromised or broken (e.g., evidence is
mishandled, lost, or tampered with), it must be documented.
 Chain breaks can impact the admissibility of evidence in court.
 Closure
 The chain of custody continues until the evidence is no longer needed for legal
proceedings.
 The final disposition of evidence, such as returning it to the owner or destroying it,
is documented.
Chain of Custody

 Legal Admissibility
 A well-maintained chain of custody is crucial for evidence to be admitted in court.
 It demonstrates that the evidence is reliable and untainted by mishandling or tampering.
 Challenges
 Defense attorneys may challenge the chain of custody, so meticulous record-keeping is
essential to counter any claims of mishandling.
 Role of Custodian
 The custodian of the evidence, typically law enforcement personnel or forensic analysts, is
responsible for ensuring its proper handling and documentation.
 Custodians must safeguard evidence to maintain its integrity.
Chain of Custody

 Continuous Monitoring: - Throughout the investigative process, the chain of

custody is continuously monitored to prevent errors or misconduct.
 In summary, the chain of custody is a systematic and comprehensive record-
keeping process that ensures the proper handling, documentation, and
preservation of physical evidence in forensic science. It is essential for
maintaining the integrity of evidence and its admissibility in legal
proceedings.