Lecture 4: CSI: Preservation and Analysis of Evidence

What is a crime scene?

The location where a crime occurred and evidence can be gathered

Types of crime scenes

• Primary: original crime location.

• Secondary: related locations after initial crime.

• Macro: large scene (entire building).

• Micro: small details (bloodstain, fingerprint)

Main goals of crime scene investigation

Determine who, what, where, how, and (least often) why

Principle of crime scene management

Every action at the scene alters it; must be methodical since there is only one chance to document original condition

General process of CSI

Securing → Assessing/Observing → Documenting → Searching → Collecting → Processing/Analyzing

Securing the scene

Protect boundaries, restrict access, prevent contamination

Assessing the scene

Survey complexity, hazards, fragile evidence, entry/exit points, weather effects

Documenting the scene

Includes notes, sketches, photography, videography

Collecting evidence

Remove/package items for storage or analysis; minimize contamination and degradation

Packaging methods

• Unbreakable bottles: small trace items.

• Paper bags/envelopes: general use.

• Airtight containers: volatile residues.

• Druggist fold: small items.

• Cardboard boxes: guns/sharp objects.

• Separate packaging: prevents cross-contamination

Chain of custody

Written record of evidence movement and handling; ensures integrity