The Crime Scene

1. The Crime Scene

2. Physical Evidence • Any object that can establish that a crime has been committed or • Provide a link between a crime and its victim or • Between a crime and its perpetrator

3. 12 stages of a crime scene search • Advanced Preparation • Approach the scene • Secure and protect • Initiate a preliminary survey • Evaluate the physical evidence • Prepare a narrative description • Photograph the scene • Prepare a sketch • Conduct a detailed search • Record and collect all the physical evidence • Conduct a final survey • Release the crime scene

4. Who is Involved in a Crime Scene? • First officer • Detective • Crime Scene Investigator • Crime Scene Reconstructionist

5. First Officer • Call for medical assistance if injuries occurred • Secure the scene • Look for perps and make arrest • Isolate large area with rope/tape • Keep all unauthorized personnel out of crime scene • Make sure no one touches anything • Call Criminal Investigators (ID unit) • Begin crime scene log and keep until after scene is processed • Make help detective question and transport witnesses to police station

6. Detective • Question witnesses • Transport witnesses to station to make a formal written statement • Develop theories on witness statements

7. Crime Scene Investigator • Lead Investigator • In charge of scene, determines boundaries and perpetrator’s entrance and exit • Record the scene • Sketching, notes, and photography • Collect and package any evidence • Later, they will testify and demonstrate all evidence at trial

8. Recording a crime scene • Photography • Unless there are injuries, nothing may be altered until all photographs are taken What to photograph? • points of entry/exit • Adjacent rooms/area • Entire room from various angles • Close up of injuries/weapons • Under body must be photographed after body is removed

9. Make sure to use photo log for documentation • Utilize various views of the scene • Photograph all evidence prior to collection • Digital Media is cheap, USE IT!!!! • Take pics from eye level

10. Special case: Corpse • Document with photos and note the precise position, location, and injuries. • Send for medical examiner who will pronounce the victim dead • Obtain victim’s clothing as evidence

11. Sketching the crime scene • Make a rough sketch • Include specific location, date, time, case identifier, preparer, weather and lighting conditions, scale or scale disclaimer, evidence • Important measurements, legend, and key • Objects are located from 2 measurements from fixed points

15. Finished Sketch • must be to scale, include everything seen in rough sketch • Also include compass reading

16. Note taking • Quick descriptions of the crime scene • May also be video recorded

17. Searching for Evidence • Searching systematically • Subdivide into segments • Circular • Grid • Make sure to search entries and exits too • Vacuum critical areas

18. Evidence Collection • Evidence must be collected in the correct methods to be admissible in court

19. Blood • Use gauze or cotton swab to obtain a sample • Allow to air dry and send to lab immediately • Put in brown paper bag or box and seal. • DO NOT use plastic containers

20. Dried Blood • If possible place entire stained area in brown paper bag. • If you can not do so, scrape dried blood onto clean paper, then put in envelope • Do not mix stains, place each stain in a different envelope • NEVER moisten stain

21. Seminal Fluids • Place in paper bags • NEVER in plastic bags

22. Hair/Fibers • All hair should be collected in small bindles and place in larger envelopes

23. Firearms/Weapons • Should be put in gun box • Knifes should be put in knife box

24. Overall rules • If it is DNA evidence, use paper • MOISTURE BAD • It will increase DNA breakdown

25. Points of Interest • Homicide • Look for hair, weapons, fibers, cross-transfer, signs of struggle • Burglary • Tool marks for point of entry • Hit and Run • Undercarriage for cross-transfer • Blood, tissue, hair, • paint and broken glass on victim

27. Chain of custody • List of all people came in contact with evidence • Each container has collector’s initial, location of evidence, and date of collection

29. Obtain Reference/Control Sample • Physical evidence whose origin is know at comparison to evidence found at crime scene • Buccal Swab – swab of inner cheek • Substrate control – uncontaminated substance, used in arson or blood stained carpets

30. Autopsy • Make sure to take fingernail scraping • Look for pathological and toxicological evidence • Head and pubic hair, presence of blood • Take vaginal, anal, and oral swabs • Recover bullets and hand swabs for gunshot residue • Pathologist – ensure correct cause of death

31. Time of death • Determined by rate of composition • Rigor Mortis • Muscles become rigid within first 24 hours, but stop after 36 hours

32. Livor Mortis/Lividity/Hypostasis • Blood settles in part of body closest to the ground • Happens in first 12 hours

33. Algor Mortis • Body temp continually loses heat at a rate of 1 – 1 ½ degree F per hour

34. Forensic Anthropology • Look at skeleton to reveal • Sex • Age • Skeletal injury of victim • Also help reconstruct facial features

35. Forensic Entomology • Study of insects and their life cycle • Help estimate time of death • Blowflies will lay eggs • Eggs will hatch into pupae stage • Effected by environmental conditions • Only give an estimated time of death