2. Preservation of
Physical Evidence
• Preservation of physical evidence refers
to the careful and systematic handling,
storage, and protection of items or
materials that may have evidentiary value
in a criminal investigation, legal
proceeding, or any situation where the
physical properties of an object may be
important.
• This process is crucial to maintain the
integrity and reliability of the evidence,
ensuring that it can be properly examined,
analyzed, and presented in court or other
3. Introduction
i. Preservation of Evidence Integrity: Proper handling ensures that
physical evidence remains unaltered, uncontaminated, and undamaged.
Any tampering or contamination can compromise the accuracy and
credibility of the evidence in court.
ii. Adherence to Legal and Ethical Standards: Maintaining a strict chain of
custody and following established procedures for evidence handling is a
legal requirement. Failure to do so can lead to evidence being
inadmissible in court, potentially undermining a case.
5 important reasons why proper evidence is essential :
4. iii. Maintaining Investigative Objectivity: Proper evidence handling helps
investigators maintain objectivity and impartiality. When evidence is
handled with care and consistency, it minimizes the risk of bias or
manipulation, ensuring a fair and just investigative process.
iv. Preserving Investigative Leads: Evidence can provide leads and clues
crucial to solving a case. Mishandling or neglecting evidence may result in
the loss of valuable information, hindering the progress of an
investigation or legal proceedings.
v. Building Public Trust: Proper evidence handling practices demonstrate
transparency, professionalism, and a commitment to upholding the rule
of law. Public trust in law enforcement and the justice system is bolstered
when it is evident that evidence is handled with care and precision.
5. Methods of preservation of physical
evidence
1.Packaging and Containment:
a. Evidence bags: Use specialized evidence bags, envelopes, or containers to safely
store and transport items like clothing, documents, drugs, and other small items. These
containers are typically made of paper plastic and have seals to prevent tampering.
b. Sealing: Seal evidence containers with tamper-evident tape or seals to ensure the
evidence remains secure and uncontaminated.
2. Biological Evidence:
a. Refrigeration or freezing: Keep biological evidence like blood, tissues, or bodily fluids
in a cool environment to slow down degradation. Refrigeration (around 4°C) or freezing
(-20°C or lower) is often recommended.
b. Air-drying: Allow wet biological evidence, such as bloodstains, to air-dry naturally at
room temperature before packaging.
6. 3.Firearms and Ballistic Evidence:
a. Unloading: Ensure firearms are safely unloaded and cleared of any ammunition
before handling.
b. Documenting: Record the condition, make, model, and serial number of firearms.
Package firearms separately to prevent damage or contamination.
c. Chain of custody: Maintain a strict chain of custody for firearms and related ballistic
evidence.
4.Trace Evidence:
a. Collection: Use specialized tools like tweezers or vacuum pumps to collect trace
evidence such as hair, fibers, or glass fragments.
b. Packaging: Place trace evidence in appropriate containers, such as bindles or vials,
and label them with detailed information.
7. 5.Arson Evidence:
a. Airtight containers: Preserve arson evidence, such as charred debris or accelerants,
in airtight containers to prevent the loss of volatile substances.
b. Documentation: Photograph and document the fire scene before collecting evidence.
6.DNA Evidence:
a. Proper collection: Collect biological samples carefully using sterile swabs or tools,
and store them in DNA-specific containers.
b. Refrigeration or freezing: Maintain DNA evidence at low temperatures to prevent
degradation.
7. Digital Evidence:
a. Imaging and copying: Create forensic images or copies of digital evidence, such as
computer hard drives or mobile phones, to preserve its original state.
b. Chain of custody: Document the handling and transfer of digital evidence and
maintain a secure storage environment.
8. 8. Firearms and Toolmarks:
a. Use proper techniques: Handle firearms and toolmarks evidence with care to avoid
altering or damaging the markings.
b. Document and photograph: Document any serial numbers, markings, or impressions
on firearms or tools.
9. Controlled Substances:
a. Sealing and labeling: Package controlled substances, such as drugs or chemicals, in
airtight containers and label them with detailed information.
b. Document quantities and appearance: Record the appearance, quantity, and
packaging of controlled substances.
10. Documents and Paper Evidence:
a. Preservation of documents: Store paper evidence in a dry, cool, and dark
environment to prevent fading, degradation, or mold growth.
b. Document handling: Use gloves and avoid unnecessary handling of paper evidence.
9. Sealing of Physical Evidence
Sealing helps to maintain the integrity and
authenticity of the evidence, ensuring that it
is admissible in court and can be used to
establish facts in a legal case.
Properly sealed evidence is less likely to be
tampered with, contaminated, or
compromised in any way, which is essential
for a fair and accurate investigation and
trial.
10. Drug test specimen bottle:
Frangible security label
detects tampering or altering
of the specimen.
Two mobile phones in a security bag or
"evidence bag"
13. Labelling
• Evidence [probably hazardous] should be
marked with a biological hazard label and that
contain items that are dangerous to human life
should be marked with a chemical hazard label.
•All packages should be sealed in such a
manner that make it quite impossible to open
them keeping seals intact.
•The sample of concerned seal should always
14. Forwarding of evidence
• The chain of custody (COC) is a
crucial documentation and
tracking system used in the field
of forensics and law enforcement
to maintain the integrity and
accountability of physical
evidence.
• The primary purpose of the
chain of custody is to provide a
clear, unbroken record of who
had possession of the evidence,
where it was located, and when it
15. •A chain of custody
document is created.
This document serves
as a log that records
every person who
comes into contact with
the evidence, along
with the date and time
of transfer. Each
