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Chapter 3: Crime Scene Investigation and Laboratory Analysis of Biological Evidence. Forensic Biology by Richard Li. Forensic Investigations Involving Biological Evidence. Requires: Crime scene examination Scene security, documentation, collection and preservation of evidence

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Presentation Transcript
forensic investigations involving biological evidence
Forensic Investigations Involving Biological Evidence
  • Requires:
    • Crime scene examination
      • Scene security, documentation, collection and preservation of evidence
    • Laboratory analysis
      • Utilizes scientific techniques for evidence examination, identification of biological fluids, and the comparison of individual characteristics

Forensic Biology by Richard Li

crime scene investigation
Crime Scene Investigation
  • Protecting and securing the scene:
    • Duty of the first officer on the scene
    • Only authorized personnel
    • Use log sheet
    • Obtain medical attention if needed
    • Proper supplies and devices must be utilized
      • E.g. Disposable suits, face mask, disposable gloves and booties

Forensic Biology by Richard Li

crime scene investigation1
Crime Scene Investigation
  • Documentation
    • Sketch
      • Rough and Finished
    • Photographs
      • Use photo log sheet
      • Use scale
    • Video

Forensic Biology by Richard Li

crime scene investigation2
Crime Scene Investigation
  • Chain of Custody- lists custody information at every point in time when evidence is handled or transferred

Forensic Biology by Richard Li

crime scene investigation3
Crime Scene Investigation
  • Recognition of biological evidence
    • Corpus delicti evidence
    • Victim-to-perpetrator linkage evidence
    • Victim-to-scene linkage evidence
    • Perpetrator-to-scene linkage evidence
    • Case-to-case linkage evidence
      • Modus operandi

Forensic Biology by Richard Li

crime scene investigation4
Crime Scene Investigation
  • Locard Exchange Principle:
    • Cross-transference of evidence occurs when a perpetrator has any physical contact with something or someone else

Forensic Biology by Richard Li

crime scene investigation5
Crime Scene Investigation
  • Searches
    • Alternate Light Source (ALS)
    • Types
      • Spiral
      • Grid
      • Strip
      • Quadrant/Zone

Forensic Biology by Richard Li

crime scene investigation6
Crime Scene Investigation
  • Collection
    • Only done after documentation is complete
    • Consider collecting entire item if small enough or mobile
    • Considerations
      • Bloodstain pattern evidence
      • Multiple analysis of evidence
      • Trace evidence
      • Control samples
      • Size of the stain
      • Wet Evidence

Forensic Biology by Richard Li

crime scene investigation7
Crime Scene Investigation
  • Packaging and Transportation
    • Goal: protect and preserve evidence
    • Avoid heat and humidity
    • Package items separately
    • Allow wet items to air dry
    • Use paper!
    • Label properly and seal

Forensic Biology by Richard Li

laboratory analysis
Laboratory Analysis
  • Identification of biological evidence
  • Comparison of individual characteristics of biological evidence

Forensic Biology by Richard Li

laboratory analysis1
Laboratory Analysis
  • Class Characteristics
    • Can be placed into a category with other similar materials
  • Individual Characteristics
    • Evidence possesses characteristics that share a common origin with a reference sample

Forensic Biology by Richard Li

laboratory analysis2
Laboratory Analysis
  • Final steps:
    • Reporting results
    • Expert testimony

Forensic Biology by Richard Li