Forensic Science Lecture Notes

Overview of Forensic Science

• Forensic science encompasses a wide range of everyday life elements.
• Key areas of focus:
  • Body fluids and tissues with DNA.
  • Fingerprints.
  • Textile fibers from clothing and furnishings.
  • Glass, paint, and other particulates.
  • Mobile phones and digital media.

Importance of Textile Fibers

• Textile fibers are significant due to:
  • Variety in types and colors, providing concrete evidence.
  • Ability to direct investigations toward relevant items.
  • Connection to DNA and marks evidence.
• Case Example: Coastal Path case
  • Key item: A pair of shorts.
  • DNA from the shorts confirmed links to the suspect and his wife.

Blood Pattern Analysis

• Blood pattern analysis provides critical insights into crime scenes:
  • Helps determine what happened and the sequence of events.
  • First step at a scene with bloodshed:
    • Visual examination.
    • Photographing the patterns for records.
• Key insights from blood patterns:
  • Indicates the source of blood (for DNA profiling).
  • Identifies necessary samples for DNA testing to manage costs.

Types of Blood Stain Patterns

1. Passive Blood Stains
   • Dripping, spotting, and splashing.
2. Blood Spatter
   • Resulting from force (e.g., gunshot, punches).
3. Contact Stains
   • Smears, swipes, and wipes from contact with wet blood.

Advances in Forensic Science

• The most significant advancement: DNA Profiling
  • Transformed evidence linking traces on clothing to individuals.
• Types of samples collected for DNA profiling:
  • Saliva, semen, blood, skin flakes.

Collection Techniques for DNA Samples

• Various methods based on circumstances and items:
  • Swabbing.
  • Cutting material.
  • Removing surface debris using sticky tape.
• Importance of careful collection to avoid contamination.

Interpretation Challenges

• Caution required when interpreting findings from trace materials:
  • Consideration of innocent explanations for presence.
  • Understanding the context of the crime scene and relationships.
  • Risk of accidental contamination affecting results.