2. Introduction to Crime Scene Investigation ILEETA Thanks to Edward E. Hueske University of North Texas Denton, Texas

3. Duties of First Officer to Scene Make scene safe for entry Provide medical attention to injured Secure scene Preserve physical evidence Detain witnesses Request assistance as needed

4. Crime Scene Investigation Team approach will be used One person must be in charge Equipment and supplies must be present Duties must be designated Search method(s) must be established Security of scene must be confirmed Priorities in processing must be established

5. The Team Approach Team leader is established prior to arrival This one’s yours, I had the last one Thanks a lot

6. Duties of Team Leader Meet with first officer for briefing Confirm security Determine legality of search (search warrant) Call for additional personnel/equipment Survey scene with first officer Note fragile evidence/establish priorities Make notes as to initial observations Work out action plan with team

7. Appropriate Crime Scene Attire Gloves Shoe covers Disposable suit Head gear Eye protection Breathing apparatus

8. Appropriate Crime Scene Behavior Do not smoke, eat, drink, etc. within the scene Do not bring equipment into scene and set down within the scene if at all possible Do not place foreign items down in scene

9. Documenting the Scene Photography Video Taping Sketching Diagramming Note Taking Report Writing

10. Scene Searches Spiral search Line (strip) search Grid search Quadrant (sector)

11. Vehicle Searches Photograph as found Begin with exterior exam/print search Divide interior into areas Undercarriage exam (hit & runs) Inventory and document items as removed Have items tested as appropriate

12. Autopsy Evidence Hair standards Blood samples – purple-topped tubes Prints Fingernail scrapings GSR test Sexual assault kit Recovered bullets, etc.

13. Collection and Packaging of Evidence Do not use plastic to package biological evidence Most evidence is best packaged by placing into a clean sheet of paper, folding, taping and placing in an envelope and sealing Package evidence separately Use sharps containers when needed Obtain required control samples Maintain a chain of custody record Use biohazard bag to dispose of contaminated items (gloves, shoe covers, etc.)

14. Crime Scene Photography First frame is data card (ea. Roll) General to specific Outside to inside Special documentation (street sign, house number, VIN tag, etc.) Remember: You can’t take too many pictures, but you can take too few!

15. Crime Scene Photography Camera back is in same plane as subject Fill frame with subject Include a scale in 1 photo & 1 w/o scale Use oblique lighting as required Use a tripod and remote shutter release Scaled Photography

16. Crime Scene Photography Painting with light Fill-flash Spray paint “shadowing” Luminol Specialized Techniques

17. Crime Scene Photography Use for night photography of large outdoor scenes Use for time exposures of impressions in dust with flashlight Painting with Light

18. Crime Scene Photography Use to show background with luminal Initial exposure of luminal reaction with lens wide open Manually fire strobe after exposure (use shield on strobe) Fill-Flash

19. Crime Scene Photography Use with available light Use for impressions in snow Use for impressions in sand or other soil Flat black or flat white works best Spray at an oblique angle Spray Paint “Shadowing”

20. Types of Physical Evidence Blood, Semen and Saliva Documents Drugs Explosives Fibers Fingerprints Firearms evidence

21. Types of Physical Evidence Glass Hair Two-dimensional and three-dimensional Impressions Body fluids and organs Paint Petroleum products Plastic bags (garbage)

22. Types of Physical Evidence Polymers & Plastics Gunpowder Residues Serial Numbers Soil and Minerals Tool Marks Vehicle Lamp Bulbs Wood & Vegetative Matter

23. The Goal of Physical Evidence Positive Identification Association Circumstantial

24. Comparative Analysis Known to Unknown or “Q” to “K” Physical comparison (physical properties/jig-saw puzzle fit) Chemical comparison Class characteristics Individual characteristics

25. Range of Conclusions Identification (common origin) Same source or a similar source (either/or) Member of same class (cannot be excluded) Exclusion (different origin)

26. Ignorance is Bliss What is a class characteristic? What is and individual characteristic? Knowledge is the key

27. Evidence and Probability Most of the time a mathematical expression is inappropriate (Highly probable vs. highly improbable) Some situations do lend themselves to a mathematical expression of probability (DNA is a prime example)

28. Probability and Statistics Coin toss – 1 in 2 probability Roll of a die – 1 in 6 probability Roll of a pair of dice to yield “snake eyes” – 1/6 x = 1/36 (1 in 36 probability) There are 4 aces in a deck of 52 cards, what is the probability of drawing an ace at random? What is the probability of drawing a king of any suit? What is the probability of drawing an ace and a king with 2 draws from a full deck?

29. Probability and Statistics DNA analysis is based on the presence of certain fragments within the DNA molecule For each fragment there is a certain frequency (probability of occurrence) within a particular ethnic group of a population If 7 different fragments are identified as being present, how is the probability of that occurring in someone else calculated?

30. Probability and Statistics A vehicle with 4 different brands of tires leaves all 4 different tread patterns at a crime scene. A suspect is arrested with a car with 4 different tires, each similar to one of the crime scene impressions. Is it possible to calculate the probability of finding the same situation on another car? What considerations are involved?

31. Negative Evidence “Absence of Evidence is not evidence of absence” Nevertheless, what is not present can provide useful information as to how a crime may have been committed Ex: No shoe impressions on driver side of vehicle but shoe impressions leaving the passenger side Faulty reasoning: no blood in trunk, therefore victim was not transported in trunk.

32. Crime Scene Reconstruction Who? What? When? Where? How? Why?

33. Crime Scene Reconstruction On-scene Off-scene Re-enactment: Live actors Mannequins