1. Crime-Scene Investigation and Evidence Collection

2. Objectives

4. Are there cars parked on the sides of the road?
What color is the pickup truck driving in the road?
Any minivans around?
What does the blue sign say?
What’s the speed limit?
Are there any pedestrians on the road?

5. Locard’s Exchange Principle
When a person comes into contact with an object or another person, a cross-transfer of physical evidence can occur
Hair, skin cells, clothing fibers, pollen, glass fragments, debris from clothing, makeup, soil
Called trace evidence
pet hair on clothes
Hair on your brush
Fingerprints on glass
Soil tracked into house
Drop of blood on t-shirt
Used tissue
Paint chips
Broken glass
Fiber from clothing

6. Evidence Classified two different ways – Direct evidence
Circumstantial evidence
Physical evidence
Biological evidence
Trace evidence

7. Direct Evidence
Firsthand observations such as eyewitness accounts or police dashboard video cameras
Confessions
Testimony by a witness in court

8. Circumstantial Evidence
Indirect evidence that can be used to imply a fact but that does not directly prove it
Link between crime scene and a suspect
Physical – Impressions, fingerprints, footprints, shoe prints, tire impressions, tool marks, fibers, weapons, bullets, shell casings
Reduces number of suspects to a specific, smaller group
Biological – body fluids, hair, plant parts, natural fibers
Makes the group of suspects very small, or reduces it to a likely individual

9. Class vs. Individual Evidence
Class – narrows identity to a group of persons or things
Ex – blood type
Individual – narrows an identity to a single person or thing
Ex – fingerprints

10. The CSI Team Police officers District attorney
Crime scene investigators
Medical examiners
Detectives
Specialists

11. The Crime Scene Investigation Team
Police officers – secure the scene
District attorney – determine whether search warrant is necessary
Crime-scene investigators – document crime scene in detail and collect physical evidence
Recorders, sketch artists, photographers, evidence collectors
Medical examiners – determine cause of death if homicide
Detectives – look for leads by interviewing witnesses and talking to crime-scene investigators about evidence
Specialists – consulted if the evidence requires their expertise
Entomologists, forensic scientists, forensic psychologists, etc.

12. The Seven S’s of Crime Scene Investigation
Securing the scene
Separating the witnesses
Scanning the scene
Seeing the scene
Sketching the scene
Searching for evidence
Securing and collecting evidence

13. 1. Securing the Scene
Responsibility of the first responder (usually a police officer)
Restricts all persons not authorized from entering
Security log of all entering and exiting
May request various experts to be sent to scene
First Priority – safety of all individuals
Second Priority – preservation of evidence

14. 2. Separating Witnesses
Witnesses must not be allowed to talk to one another!
Questions to ask:
When did the crime occur?
Who called in the crime?
Who is the victim?
Can the perpetrator be identified?
Where were you when you observed the crime scene?

15. 3. Scanning the Scene
Scan the scene to determine where photos should be taken
Primary crime scene – where crime took place
Secondary crime scene – location linking to crime
Ex: Primary scene - front of store where robbery took place
Secondary scene – home of suspect
Ex: Primary scene – location of murder
Secondary scene – location where corpse was found

16. 4. Seeing the Scene Crime examiner needs to see whole scene
NEEDS TO BE IN UNALTERED POSITION!!!
Photos of overall area
Close-up photos
Photos with and without a measuring ruler
View of crime scene from different angles and distances
Close-up photos of any evidence and bodies
Photos need to be taken before evidence or body is moved

17. 360 view

18. 360 view

19. 360 view

20. 360 view

21. 360 view

22. 360 view

23. 360 view

24. Evidence

25. Evidence

26. Evidence

27. Evidence

28. Evidence

29. Evidence

30. Evidence

31. Evidence

32. Evidence

33. Evidence

34. Evidence

35. Evidence

36. Evidence

37. Evidence

38. 5. Sketching the Scene
Rough sketch – notes position of body and any other evidence
All objects measured from two immovable landmarks
North should be labeled, scale included for distance
Doors, windows, furniture
If outdoors, position of trees, vehicles, hedges, other structures
Drawn AT the scene
Also include – name, date, location, conditions outside or inside

39. Figure 2–4 Rough-sketch diagram of a crime scene
Figure 2–4  Rough-sketch diagram of a crime scene. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C.,

40. 5. Sketching the Scene
Final Sketch – include all the aspects of a rough sketch but more accurate
Possible for presentation in court
Computer programs available now
Drawn in the lab AFTER searching the crime scene
Note-taking also occurs throughout entire process

41. Figure 2–5 Finished-sketch diagram of a crime scene
Figure 2–5  Finished-sketch diagram of a crime scene. Courtesy Sirchie Finger Print Laboratories, Inc., Youngsville, N.C.,

42. 6. Searching for evidence
Scene should be walked and location of evidence marked, photographed, and sketched
Patterns:
Spiral
Grid
Linear
Quadrant or Zone
Single investigator – grid, linear, or spiral pattern
Group of investigators – linear, zone, quadrant

44. 7. Securing and Collecting Evidence
All must be properly packaged, sealed, and labeled
Liquids and arson – stored in airtight, unbreakable container
Biological evidence – stored in breathable containers so air can dry out
Wet evidence – stored in paper and allowed to air dry
NEVER place wet evidence in an airtight container; will cause mold and degrade DNA
Paper bindle – paper used to store evidence
Placed into evidence bag and labeled

45. Standards
There are many standards for collecting different types of evidence
Example: National Institute of Justice

46. Control Samples Obtained from the victim for the purpose of exclusion
Ex - blood samples found on a victim or at crime scene compared to victim’s blood
If they match, sample is victims and no further tests run
If not, may have come from suspect and further testing is completed!

47. Evidence Log Case number Item inventory number Description of evidence
Name of suspect
Name of victim
Date and time of recovery
Signature of person recovering evidence
Signature of any witnesses present during collection

48. Chain of Custody
Each person who handles the evidence must be recorded properly
When evidence is found – marked with proper information and placed in a collection bag
Container is sealed and collector’s signature is written across sealed edge
Next person responsible opens at a location other than sealed edge, completes exam, reseals in new packaging and signs chain of custody log!
Pattern continues!

49. Chain of Custody EXTREMELY important for courtroom!
All who handled evidence could be asked to appear in court
Process must show evidence was handled properly and every person handling it was recorded

51. Analyze the Evidence
FBI crime lab is one of largest forensic labs in the world!
Forensic Lab Technicians – specialized and process only one type of evidence
Lead detective – lab results sent to him
Looks at evidence and attempts to determine how it fits into overall crime scenario
Must consider all possible interpretations for evidence

52. Use of Evidence Evidence compared to witness’ statements
Can link a suspect to scene or a victim
Establish the identity of a victim
Confirm verbal witness testimony
Acquit the innocent

53. Crime Scene Reconstruction
Forms a hypothesis of the sequence of events from before the crime was committed through its commission
Evidence does not lie, but could be staged!
Evidence is used to determine overall crime scenario

54. Crime Scene Safety THE CRIME SCENE
The increasing spread of AIDS and hepatitis B has sensitized the law enforcement community to the potential health hazards that can exist at crime scenes.
In reality, law enforcement officers have an extremely small chance of contracting AIDS or hepatitis at the crime scene.
The International Association for Identification Safety Committee has proposed guidelines to protect investigators at crime scenes containing potentially infectious materials that should be adhered to at all times.
THE CRIME SCENE

55. Crime Scene Safety
At crime scenes where blood or body fluids involved: latex gloves and shoe coverings should be warn.
If potentially infectious dust or mist encountered: particle mask/ respirator, goggles, or face shield recommended also.
Personnel should be aware of sharp objects, knives, hypodermic syringes, razor blades, etc and place them in appropriate container with label.
Red biohazard bag should be used for disposal of contaminated gloves, clothing, masks, pencils, etc. and removal to approved biohazardous waste pickup.

56. Crime Scene Safety
5. Note-taking should be done while wearing uncontaminated gloves to avoid contamination or pens, pencils, notebook, paper, etc.
6. If personal protective equipment (PPE) becomes torn, must be removed immediately and person must decontaminate the potentially contaminated body area with recommended solution.
No eating, drinking, smoking, or applying makeup at scene of a crime.
All nondisposable items (lab coats, towels, personal clothing) that may be contaminated are placed in a yellow plastic bag, labeled “Infectious Linen” and laundered by a qualified service.