Forensic Science Notes

Introduction to Forensic Science

Faculty of Life Sciences & Medicine

  • Prof. Gillian Tully, CBE PhD Hon FCSFS Hon FFFLM
  • Course: 5MRFFS02
  • Department: Analytical, Environmental and Forensic Sciences

The “Golden Hour” Principle

  • Definition: The critical time window immediately following a crime during which evidence can be collected effectively.
  • Objectives:
  • Prevent loss of evidence
  • Quickly identify and remand suspects
  • Obtain witness testimony while still fresh
  • Collect CCTV footage before deletion
  • Secure crime scene to prevent contamination
  • Challenges:
  • Delays in crime discovery
  • Immediate attendance not feasible for less serious crimes

Chain of Custody

  • Definition: A documented record detailing all individuals who handled the evidence from collection to courtroom presentation.
  • Key Aims:
  1. Preservation of Evidence: Prevent degradation or loss.
  2. Avoid Contamination: Maintain integrity of the evidence.
  3. Maintain Chain of Custody: Ensure proper tracking and accountability.

Preservation

  • Ensures evidence is protected and properly collected to maintain integrity for legal proceedings.

Types of Crime Scene

  • Outdoor:
  • Highly susceptible to evidence loss and contamination.
  • Evidence can be easily destroyed by environmental factors.
  • Indoor:
  • Less susceptible and easier to secure.
  • Some scenes may be hazardous or traumatic.

Controlling the Scene

  • Control over the crime scene is foundational in forensic investigations.
  • Issues to Manage:
    • Pre-existing DNA
    • DNA introduced by investigators
    • Post-seizure contamination
  • Access Control: Strict management of who enters the scene.
  • Personal Protective Equipment (PPE): Mandatory usage and documentation.

Personal Protective Equipment (PPE)

  • Items include:
  • Scene suit
  • Overshoes
  • Inner and outer gloves
  • Mob cap
  • Face mask
  • Goggles
  • Body armor
  • Hazmat protection

Equipment

  • Must be cleaned after each use with a documented regime.
  • Should only enter the crime scene when necessary and stored in a clean environment.

Consumables

  • Definition: Sterile items used in evidence collection (e.g., swabs).
  • Must be stored and transported appropriately to prevent contamination.

Documenting the Scene

  • Photography:
  • Capture various angles: long-range, mid-range, and close-up.
  • Use scales for context.
  • Video Documentation:
  • Slow walkthroughs of the scene; sound is usually off.
  • Captures layout and evidence; includes various formats like CCTV.
  • 3D Scanning:
  • Records scenes in 360° for immersive experience; allows for precise measurements.
  • Sketches/Plans and Diagrams:
  • Must precisely record evidence locations; orientations may be critical.

Contemporaneous Notes

  • Definition: Accurate records made at the time of the event.
  • Importance: Helps maintain the integrity and reliability of testimonies and evidence presentation.
  • Should capture all relevant details about the investigation.

Notebook Rules

  • Use black ink, no erasures or loose pages, secure all information.
  • Ensure notes are thorough and follow prescribed formats.

Packaging and Labelling

  • Importance:
  • Protects evidence from damage and preserves integrity.
  • Unique identification through clear labeling.
  • Maintains continuity of the evidence.

Packaging Tips

  • Keep complainant and suspect samples separate.
  • Limit handling and package each item separately to prevent contamination.

Tamper Evident Bags (TEB)

  • Used for securing and displaying essential information about the evidence, ensuring continuity and integrity.

Special Packaging Needs

  • Sharp Objects: Use rigid and leak-proof containers to prevent injury.
  • Body Fluid Evidence: Secured and sealed in bags with biohazard tape.
  • Drugs of Abuse: Packaged in paper bindles or suitable containers.
  • Fire Evidence: Requires double bagging to prevent evaporation.
  • Electronic Devices: Should not be switched off; use Faraday bags for protection.

Transportation and Storage

  • Transportation:
  • Dry exhibits must be kept dry; wet exhibits frozen.
  • Use clean transport bags to maintain chain of custody.
  • Storage:
  • Logged electronically to maintain continuity.
  • Evidence retention standards vary depending on case type (7 years for volume crimes, 30 years for serious crimes, indefinite for unresolved major crimes).

Additional Resources

  • Forensics Examined in Crime Scene Investigations, WIRED (YouTube links provided)

Questions

  • Encouragement to engage and ask for clarifications on the topics covered.