Forensic Biology by Richard Li

1. Chapter 3: Crime Scene Investigation and Laboratory Analysis of Biological Evidence Forensic Biologyby Richard Li

2. 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

3. 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

4. Crime Scene Investigation • Documentation • Sketch • Rough and Finished • Photographs • Use photo log sheet • Use scale • Video Forensic Biology by Richard Li

5. 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

6. 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

7. 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

8. Crime Scene Investigation • Searches • Alternate Light Source (ALS) • Types • Spiral • Grid • Strip • Quadrant/Zone Forensic Biology by Richard Li

9. 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

10. 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

11. Laboratory Analysis • Identification of biological evidence • Comparison of individual characteristics of biological evidence Forensic Biology by Richard Li

12. 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

13. Laboratory Analysis • Final steps: • Reporting results • Expert testimony Forensic Biology by Richard Li