1. The Crime Scene

2. Catalyst 10/1/13
Question: Differentiate between class and individual evidence.
Answer:

3. What do you think happened? Why?

4. Locard’s Principle Dr. Edmond Locard
Director of the world’s first forensic lab in France
Came up with the idea that when a person comes into contact with an object or another person, a cross-transfer of physical evidence can occur.

5. 2 Main Types of Evidence
1-Direct
2-Circumstantial

6. Evidence Main types (continued) 1-Direct evidence
2-Circumstantial evidence
Trace evidence
Class evidence
Individual evidence

7. Direct Evidence Consists of firsthand observations
In court, this evidence involves testimony by a witness about what that witness personally saw, heard, or did. (NO intermediary, directly from example to the investigator)
Examples:
Eyewitness accounts
Police dashboard video
Confessions

8. Circumstantial Evidence
Indirect evidence that can be used to imply fact but does not directly prove it
May provide a link between a crime scene and a suspect
Only suspect and victim actually see it left at crime scene
Can be physical or biological

9. Circumstantial Evidence (cont)
Examples:
Finding a suspect’s gun at the site of a shooting
Biological evidence:
Body fluids, hair, plant parts, and natural fibers
Physical evidence:
Fingerprints, footprints, shoe impressions, tire impressions, bullets, and tool marks

10. Trace Evidence (type of Circumstantial)
Type of Circumstantial evidence
Physical transfer of material
Examples:
Hair
Fingerprints
Soil
Blood
Kleenex
Fiber
Glass
Paint chips

11. Class Evidence (type of Circumstantial)
Narrows an identity to a group of persons or things
Cannot specify a single person
Only excludes people that do not fit the category
Examples:
Blood types
Hair color
Common fibers
Shoe prints

12. Individual Evidence (type of Circumstantial)
Narrows identity to a single person or thing
Examples:
DNA
Complete fingerprints(not partials)
Tool marks
Anything torn or broken and left at the scene

13. Catalyst 10/2/13
Question: What is the difference between circumstantial and direct evidence?
Answer:

14. Forensic Activity-ROBBERY!
A large appliance store was robbed, but no forced entry was apparent. A tab from a beverage can was found by one of the outside doors, causing investigators to assume that it may have been used to wedge the door for later access. The next day, the driver of a vehicle was pulled over for a minor traffic violation. In the car were a number of empty soda cans, all with their tabs removed.

15. Answer in your groups!
Can you verify that whoever robbed the store worked there? Explain your answer.
Did the robber have some connection to anyone that worked there? Explain your answer.
Can the tab found at the crime scene be associated with the empty soda cans in the suspect’s car? Why or why not?
How would you go about trying to individualize the tab to the can?
How strong of a case can you, the forensic investigator, establish against the suspect? Explain your answer.
What kind of evidence is the tab; class or individual? Explain your answer.
What additional evidence could be collected from the tab that was left at the crime scene to strengthen this case? Explain how your answer would help the prosecution.

16. 5 S’s of Crime Scene Investigation
Securing the scene
Separating the witnesses
Scanning the scene
Sketching and photograph the scene
Searching and collecting of evidence

17. 1-Securing the Scene The most important job at a crime scene
Performed by the first officer at the scene, called the first responder
Safety of all individuals in first priority
Preservation of evidence is second
Finally record the scene

18. 2-Separate the witnesses
Separation prevents them talking to each other
Each witness will be asked about the crime scene and what they observed

19. 3-Scan the Scene Determine if and where photos should be taken
Determine if there may be a secondary crime scene
Person killed at a party (primary scene)
Dumped in a lake (secondary scene)

20. 4-Sketching the Scene First is a Rough Sketch done at the scene
Must be accurate and to scale
Note body, evidence, doorways, windows, walls, trees, cars, and movable objects
Distances should be measured and recorded
Case number, date, location, and time should also appear on the sketch

21. Rough Sketch

22. Final Sketch
Usually done by a computer
Presented in court

23. Photographing the Crime Scene
All evidence
Doors and windows
Anything out of the ordinary

24. 5-Searching and Collecting Evidence
Must be properly packaged, sealed, and labeled
Dry evidence - placed in a paper bindle, put into a plastic bag, sealed with tape, labeled
Wet evidence - placed in a paper bag to allow drying, then treated like dry evidence
When bag is sealed, person must sign their name across the seal

25. Making a paper bindle
Fold the paper into thirds both directions so you end up with 9 rectangles
Place your evidence in the middle and fold paper around it
Do you have any further questions on how to create a paper bindle?

26. Collecting Evidence
Evidence Label

27. Chain of Custody Must be attached to evidence container
Starts with person who finds evidence
The next person to use or analyze the evidence must fill out a label
Ensures evidence is handled correctly
If it is not handled correctly, can be traced to who’s responsible

28. Crime Scene Reconstruction
Crime scene reconstruction involves:
forming a hypothesis of the sequence of events from before the crime was committed
BEWARE of staged crimes (cover ups)

29. Staged Crime Scenes
When the lab results do not match up with the testimony of witnesses, it can mean the crime was staged
Common examples include:
Staging a fire—to cover bankruptcy.
Staging a suicide—to cover a murder.
Staging a burglary—to collect insurance money.

30. Staged Crime Scenes (cont)
To help determine whether a crime scene was staged, consider:
Whether the type of wound found on the victim matches the weapon employed.
Whether the wound could have been easily self-inflicted.
The mood and actions of the victim before the event.
The mood and actions of a suspect before the event.