Collection of Evidence Publisher's PP (1)

Chapter Overview

  • This chapter provides an in-depth analysis of the collection of crime scene evidence, outlining its importance, types, and proper handling methods.

Collection of Crime Scene Evidence

  • Importance of Physical Evidence

    • Physical evidence helps in establishing whether a crime has been committed.

    • Provides links between victims, perpetrators, and the crime scene.

  • Recognition and Preservation

    • Investigators must be able to recognize and properly preserve physical evidence for analysis.

    • The lack of proper preservation can undermine forensic analysis, regardless of available technology.

  • Diversity of Physical Evidence

    • It is challenging to enumerate all items that can serve as physical evidence; almost anything can be pertinent to a case.

    • Some common categories include:

      • Blood, semen, saliva

      • Documents

      • Drugs

      • Explosives

      • Fibers

      • Fingerprints

      • Firearms and ammunition

      • Glass

Types of Physical Evidence

  • Categories:

    • Biological Evidence:

      • Blood, semen, saliva

    • Chemical Evidence:

      • Drugs, explosives, adhesives

    • Trace Evidence:

      • Fibers, hair, soil, minerals

    • Marking Evidence:

      • Tool marks, fingerprints, foot impressions

    • Miscellaneous:

      • Vehicle lights, wood

Procedures for Collection

  • Visible Evidence:

    • Many types of evidence are apparent while others require laboratory examination.

  • Trace Evidence:

    • It's crucial to collect potential carriers of trace evidence such as clothing and vacuum sweepings.

  • Proper Handling:

    • Prevent contamination, breakage, or loss by using protective gloves and sanitized equipment.

    • Maintain the original condition of the evidence whenever possible.

Packaging of Evidence

  • Separate Containers:

    • Each piece or similar items from different locations must be packaged separately to prevent damage and contamination.

  • Available Tools:

    • A range of packaging materials should be available to suit various evidence types.

    • Common containers include:

      • Unbreakable plastic pill bottles for small items

      • Manila envelopes, screw-cap glass vials for trace evidence

    • Sealability:

      • Sealable plastic bags and druggist folds of paper for trace evidence.

    • Hazardous Evidence:

      • Evidence from arson scenes should be in airtight containers to preserve the evidence.

Handling Biological Evidence

  • Dehydration Risks:

    • Blood or biological materials in airtight containers may promote mold growth.

    • Use cardboard boxes, paper bags, or manila envelopes and air dry in the lab.

  • Contamination Risks:

    • Key concerns with DNA evidence require careful handling to prevent foreign DNA introduction.

Chain of Custody

  • Definition:

    • A record of all individuals who handled the evidence.

  • Importance:

    • Ensures continuity of possession to maintain evidential integrity during court presentations.

  • Procedures:

    • Proper documentation and identification of each evidence item are crucial.

Obtaining Reference Samples

  • Need for Standards:

    • Reference samples are necessary for comparison, allowing forensic labs to match unknown evidence with known sources, e.g., a suspect's blood or hair.

    • Thorough sampling of reference materials is essential for accurate analysis.

Crime Scene Safety Protocols

  • Health Hazards:

    • Investigators encounter biological specimens of unknown origin; caution and protective equipment are mandatory.

  • Hot Zone Awareness:

    • The crime scene's active areas require full protective gear, including masks and suits.

  • Maintenance of Cleanliness:

    • Dispose of contaminated materials in red biohazard bags and apply universal precautions to every sample.

  • Cut Hazards:

    • Be vigilant for sharp objects and prohibitions on eating/drinking at the crime scene.

  • Updating Safety Procedures:

    • Annual training and health inspections are advised for crime scene safety equipment users.

Search and Seizure Protocols

  • Legal Framework:

    • Evidence removal must comply with Fourth Amendment protections against unreasonable searches and seizures.

  • Exceptions:

    • Justified warrantless searches include emergencies, loss prevention, lawful arrests, or consented searches.

Landmark Cases in Search and Seizure

  • Mincey v. Arizona:

    • The Court ruled against the legality of a four-day search without a warrant, emphasizing the necessity of judicial oversight.

  • Michigan v. Tyler:

    • Courts found initial searches to be legal but later searches were ruled illegal absence of warrants.