Collection of Biological Evidence

Collection of Biological Evidence

Understanding Biological Evidence

  • Biological Evidence refers to samples of biological material—such as hair, skin, blood, saliva, and other bodily fluids—collected at a crime scene.
  • Due to its nature, biological evidence can provide crucial information about the identity of a person involved in the crime and help establish a physical link between the crime and the suspect.
  • Key determinants in examining biological evidence are DNA analysis and blood spatter analysis, both of which are of paramount importance in forensic sciences.

Collection Techniques

Packaging and Transporting

  • Biological evidence should be allowed to air dry before packing to prevent the growth of mould which could degrade the DNA.
  • Each item of biological evidence should be packaged separately to avoid cross-contamination.
  • It is vital to remember that biological evidence should not be exposed to extreme temperatures or humidity, as these can damage the evidence.
  • The use of breathable containers, such as paper bags and envelopes, is preferable over plastic bags for storing biological evidence to avoid condensation.

Wet and Dry Samples

  • For wet samples, use a clean, sterile swab moistened with distilled water, sterilized saline, or other suitable sterile solutions to collect the biological material.
  • Dry samples, on the other hand, can be collected using dry, sterile swabs, or swabs moistened with a sterile solution.
  • The evidence collected on swabs should be air-dried before packaging.

Use of Personal Protective Equipment (PPE)

  • The use of Personal Protective Equipment (PPE), such as gloves, disposable gowns, shoe covers, and masks, is vital to prevent the collection officer’s DNA from contaminating the evidence.
  • Gloves must be changed between collection of different samples to avoid cross-contamination.

Preservation of Biological Evidence

  • To restrict the degradation of biological evidence, it must be stored as soon as possible post-collection.
  • It is important to include a detailed label on each evidence package that includes the case number, item number, location, date, and collector’s initials or signature.
  • For best preservation, biological evidence should be refrigerated if it cannot be processed immediately.

Final Thoughts

  • The accurate collection, preservation, and analysis of biological evidence are vital to forensic investigations.
  • This requires careful attention to detail, proper usage of tools and techniques, and stringent adherence to established protocols. These skills are of the essence in maintaining the integrity of the evidence and ensuring its validity in legal proceedings.