The Crime Scene

1. The Crime Scene Chapter 2

2. The Crime Scene • Physical Evidence – an object that can establish a crime has been committed or can link a crime and its victim or its perpetrator • massive objects or microscopic traces • First step is to recognize the presence of physical evidence

3. Securing the Scene • Police usually the first responders: help or hinder • Priority to preserve life • Treat injuries • Move victims from danger ***Risk of contaminating or destroying evidence

4. Securing the Scene • Secure and isolate crime scene • Remove non-essential personnel • Prevent traffic that could destroy evidence • Establish boundaries

5. Securing the Scene • Remove suspects from the scene • To preserve evidence and avoid prejudicing eyewitness testimony • Detain eyewitnesses • Proper procedure: alone and separated from other witnesses

6. Preliminary Examination • Evaluate the scene • Perpetrator’s path of entry and exit • Initial walk-through • Limited amount of time to work a crime scene • Record the scene: photography, sketches, and notes

7. Photography • Most important prerequisite: crime scene must be unaltered • Limited: people and money • Objects not to be moved until photos taken from all necessary angles • Photos show position and location of evidence • Close-ups record details • Size is significant: need reference point

8. Sketches • Post-photography • Rough Sketch: Draft, essential info and measurements • Drawn at crime scene • Shows all recovered items of physical evidence • Other important features

9. Sketches • Final Sketches: precise rendering of crime scene • Drawn to scale • Not done at crime scene • Concern for aesthetic

10. Notes • Constant activity throughout processing • Include detailed written description of location where physical evidence is recovered • Time • Who • Position • How packaged

11. The Search • Looking for the Evidence ~ thorough and systematic • Some evidence only detected in lab: important to collect carriers (vacuum sweepings) • Search pattern depends on size, location, and number searching

12. Beyond the Crime Scene • Search for evidence extends to autopsy • Establish manner and cause of death • Tissues and organs sent for pathology and toxicology

13. Beyond the Crime Scene • Items collected from victim and sent to forensic laboratory • Clothing • Fingernail scrapings • Head/pubic hairs • Blood - DNA typing • Vaginal, anal, oral swabs (sex-related crimes) • Recovered bullets • Hand swabs ~ GSR analysis

14. Packaging the Evidence • Separate containers prevent contamination • Submitted intact – not removed from garments, weapons, etc. (precarious, large structures) • Tools: Pill bottles, glass vials, manila envelopes, sealable plastic bags • Mailing envelopes bad  • Druggist fold • EXCEPTIONS • ~ fluids (bloodstains, semen) dried, packaged in paper • ~ Charred debris – sealed in airtight container

15. Chain of Custody • List of persons who are in possession of evidence • Must be maintained at all times • Record location, date/time, who collected • Any transfer of evidence must be recorded ~ kept to minimum

16. Additional Samples • Reference Samples: Physical evidence with known origin to compare to crime-scene evidence • Blood, hair, fiber • Substrate control: uncontaminated material near area of evidence recovery • removes background (accelerants and arson) • Evidence submitted by personal delivery or mail (postal restrictions) • Proper forms

17. Forensic -ologies • Pathology: The M.E. or coroner • 4 (5) types of death: • Natural, homicide, suicide, accidental, unexplained • Investigates unnatural, unexplained death • Rigor Mortis • Livor Mortis • Algor Mortis • Forensic Anthropology • ID skeletal remains • Forensic Entomology • Insect morphology – establish TOD