Collection of Physical Evidence

Collection of Physical Evidence

  • The collection of physical evidence is a crucial step in the forensic process and often relies heavily on the efficiency and effectiveness of forensic investigators.
  • Physical evidence can include a wide range of materials such as hair, fibers, fingerprints, footprints, glass fragments, and bodily fluids.
  • The evidence should be collected in a manner that preserves its original form and protects it from contamination or damage.

Securing the Crime Scene

  • A preliminary step in the collection of evidence is securing the crime scene, a process aimed at preserving as much of the scene and subsequent evidence in an untouched state, as it was found.
  • Crime scene perimeters should be established, and unauthorised individuals must not be allowed to enter the scene.
  • Documenting the crime scene is vital before any physical interaction occurs; this includes photography, sketching, and note-taking.

Identifying Physical Evidence

  • Proper identification of physical evidence is a key part of the process.
  • Investigators should systematically search for evidence, taking note of anything unusual or out of place.
  • Various types of search methods can be employed, such as grid, linear, quadrant or spiral searching, depending on the nature and size of the crime scene.

Collection Methods

  • The methods of collection often depend on the type of evidence.
  • Trace evidence like hair or fibers should be picked up with tweezers or forceps and placed in bindle paper or envelopes.
  • Fingerprint evidence should be lifted using fingerprint powder and tape, or other techniques such as fuming, depending on the surface.
  • Bodily fluids should be swabbed with sterile swabs and placed in sterile tubes or containers.
  • Bulkier evidence such as weapons or large objects should be bagged and labelled accordingly.
  • It’s important to avoid contact with the evidence, especially with bare hands, to prevent contamination.

Labelling and Packaging

  • Each piece of evidence should be labelled with a unique identifier, date and time of collection, and the name of the investigator.
  • For packaging, each piece of evidence should be individually packaged to avoid cross-contamination.
  • It’s imperative to handle evidence delicately and pack securely to prevent loss, damage, or alteration during transportation to the laboratory for further analysis.

Chain of Custody

  • The chain of custody is a crucial concept in forensic collection and refers to the chronological documentation of a piece of evidence.
  • This includes outlining every person who has had access to the evidence from the time of collection to the end of investigation or trial.
  • A break in the chain of custody can question the integrity of the evidence, causing it to be ineligible in legal proceedings.


  • Proper identification, collection, labelling and securing of evidence ensures the integrity and reliability of the evidence.
  • Comprehensive documentation of actions taken from the start to the end of the process is a critical part of the job.
  • This thorough process in effect ensures the most accurate and reliable interpretations of the evidence in later stages of investigation or legal proceedings.