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.

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.

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.

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.

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.