Crime Scene Investigation (CSI) Guide

Introduction to Crime Scene Investigation

• Crime scenes can include:
  • Bodies washed up on shores.
  • Fires, like those in meth labs.
  • Car accidents.
• Systematic examination is crucial to uncover evidence.
• Collaboration between case investigators and crime scene personnel is essential to:
  • Define and secure evidence areas.
  • Examine and document the scene.
  • Collect and preserve evidence.
• Thoroughness impacts the determination of facts and the legal process.

Principles of Crime Scene Investigation

• Locard's Exchange Principle: "Every contact leaves a trace."
• Associative evidence links people to scenes.
• Reconstructive evidence helps understand actions at the scene.
• Control samples can be circumstantial evidence.
• Example: A burglary linked through glass fragment patterns found on a suspect.
• Eliminating non-perpetrators is important using control samples.

Gauging Evidence Value

• Unique Evidence: Helps narrow suspect possibilities, such as tire impressions.
• Probability: Low chance evidence (e.g., DNA) is very valuable.
• Inconsistencies: Out-of-place items (e.g., cigarette butt at a non-smoker victim's scene).
• Physical Match: Trace evidence matching items at the scene.

Purpose and Timing of Crime Scene Investigation

• Helps recreate crime scenes and establish event sequences.
• Types of scenes include burglaries, violent crimes, suicides, etc.
• Case facts may change initial theories and require multiple scene investigations.
• Secondary crime scenes exist if the primary scene is unknown.

Crime Scene Investigation Process

Evidence Collection Samples

• Biological: Blood, body fluids, hair.
• Latent prints: Fingerprints, footprints.
• Trace evidence: Fibers, soil, glass.
• Digital: Phone records, emails.
• Tools, drugs, firearms evidence.

Collection Process Example (e.g., Burglary)

1. Photograph and document.
2. Collect trace materials at entry points.
3. Swab for DNA evidence.
4. Collect items with biological evidence.
5. Locate and collect latent fingerprints.

Crime Scene Examination Roles

• Role of detectives and specialized personnel (photographers, DNA, trace evidence experts).
• No national standards in the US, but certification through IAI is available.

Conducting Crime Scene Investigations

• Steps:
  1. Establish scene dimensions and safety.
  2. Establish security.
  3. Plan and coordinate.
  4. Conduct a primary survey.
  5. Document and process the scene.
  6. Conduct a secondary survey.
  7. Record and preserve evidence.

Testing Evidence

• Most valuable evidence sent to forensic labs.
• Presumptive Tests: Initial scene tests to identify substance types.
• Technology aids in on-site testing, reducing lab submissions.

Expectation from Crime Scene Investigation

• Detailed scene documentation and evidence collection.
• DNA profiling enhances trace and biological evidence value.
• Crime investigation is a lengthy process.

Limitations

• Crime scenes can be chaotic; conditions may deteriorate evidence.
• DNA/fingerprints may not always identify perpetrators.
• Evidence collection may require compromises.

Quality Control and Assurance

• Ensuring thorough investigation through debriefings and inventory logs.
• Maintaining chain of custody for evidence integrity.

Legal Aspects of Scientific Evidence

• Frye Standard: General acceptance of scientific methods.
• Federal Rules (Rule 702): More flexible than Frye, focuses on expert's knowledge and method reliability.
• Daubert Standard: Judges as gatekeepers; considers science, error rates, acceptance standards.

Role of Expert Witnesses

• Experts qualified by training and experience.
• Witnesses must understand and explain complex evidence clearly.
• The admissibility of an expert is determined by the court.

Additional Resources

• Various publications and online resources available for further reading on CSI.

Acknowledgments

• Contributions from leading forensic and law enforcement experts.