Collecting Evidence

RECAP: SEARCHING THE CRIME SCENE

  • Factors influencing search methods:
    • Environment
    • What is being searched for?
    • Number of personnel available
    • Terrain
    • Exigency
    • Swath size (area a searcher can effectively cover)

TYPES OF CRIME SCENE SEARCH PATTERNS

  • Physical nature of the crime scene suggests appropriate search method.

IMPORTANCE OF EVIDENCE RECOVERY

  • More evidence improves understanding of the crime.
  • Selectivity in evidence collection is crucial; educated decisions prevent oversight.

DNA EVIDENCE CONSIDERATIONS

  • High public expectations for DNA and fingerprints in all cases are often unrealistic.
  • Not all crime scenes yield DNA, and analysis can be resource-intensive.

TRIAGE FOR DNA EVIDENCE

  • Prioritization mechanisms:
    • Severity of offense
    • Type and probative value of evidence
    • Urgency in addressing public risk.

EVIDENCE COLLECTION GUIDELINES

  • Focus on items for lab analysis:
    • Collect original items if possible (Best Evidence Rule).
    • Document thoroughly to minimize contamination.
    • Collect both questioned and known samples.

TRACE EVIDENCE COLLECTION

  • Methods include:
    • Forceps, tweezers, hand collection, tape lifts, vacuuming.
    • Document and collect both questioned and known samples.

MINIMIZING CONTAMINATION

  • Keep evidence in original state:
    • Change gloves frequently; use clean tools between collections.
    • Package items separately to avoid cross-contamination.

PRIMARY AND SECONDARY TRANSFER

  • Evidence may transfer during the crime and search.
  • Collect large items before trace evidence to avoid contamination.

DRUGGIST/PHARMACIST FOLD

  • Technique for primary packaging of evidence to prevent loss.

MAXIMIZING INFO, MINIMIZING CONTAMINATION

  • Key practices:
    • Use appropriate containers (manila envelopes, sealable bags).
    • Allow wet items to air dry before packaging.

QUESTIONED AND KNOWN SAMPLES

  • Essential for comparison; include elimination samples from search personnel.

COLLECTION OF FIREARMS

  • Safety first; photograph before unloading.
  • Transport in original state when possible, especially if submerged.

FIBRE EVIDENCE

  • Types: natural (plant/animal) and man-made.
  • Primary and secondary transfers; identification and preservation of potential carriers of fibres are crucial.

SEALED EVIDENCE CONTAINERS

  • Must prevent tampering; clearly labelled and sealed.

EVIDENCE DOCUMENTATION

  • Record detailed information, including case number, item description, collection dates, and collector name.

CHAIN OF CUSTODY

  • Essential for court integrity; maintain detailed records from discovery to court presentation.