1. The Jon Benet Ramsey Case
Catalyst:
What were the issues with the original investigation?
What went wrong?

2. VIDEO What new evidence came into play in the case?
How does this new Touch DNA technology work?
Why is gathering as much evidence as possible important?

3. Crime Scene Investigation
Do you think the Ramseys should have been exonerated? Why or why not?

4. Chapter 2 Crime Scene Investigation and Evidence Collection 08.18.2008
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Forensic Science: Fundamentals & Investigations, Chapter 2

5. Chapter 2 Crime Scene Investigation and Evidence Collection By the end of this chapter you will be able to:
summarize Locard’s exchange principle
identify four examples of trace evidence
distinguish between direct and circumstantial evidence
identify the type of professionals who are present at a crime scene
summarize the three steps of a crime scene investigation
explain the importance of securing the crime scene
identify the methods by which a crime scene is documented
demonstrate proper technique in collecting and packaging trace evidence
describe how evidence from a crime scene is analyzed
All Rights Reserved South-Western / Cengage Learning © 2009
Forensic Science: Fundamentals & Investigations, Chapter 2

6. Vocabulary
Crime scene investigation: recognize, document, and collect evidence at crime scene.
Trace Evidence: small but measurable amts. Of phys./bio. crime scene
Direct Evidence: firsthand obs. / video camera accounts of crime
Circumstantial Evidence: indirect evidence that implies fact (but doesn’t prove it)
Forensic Science: Fundamentals & Investigations, Chapter 2

7. Principle of Exchange
Dr. Edmond Locard, director of the world’s first forensic lab (1910, Lyon, France), established the idea of the exchange principle; namely that:
When a person comes in contact with an object or another person, a cross-transfer of physical material can occur.
Study of the material can determine the nature and duration of the transfer.
Forensic Science: Fundamentals & Investigations, Chapter 2

8. Types of Evidence
Statements of a witness in court would be direct evidence.
Indirect or circumstantial evidence, such as a fingerprint (physical evidence) or blood or hairs (biological evidence), would imply something, and is called trace evidence.
Forensic Science: Fundamentals & Investigations, Chapter 2

9. Types of Evidence Class Individual Identifies group of person/things
Identifies specific person/thing
Forensic Science: Fundamentals & Investigations, Chapter 2

10. Types of Evidence Class Individual Identifies group of person/things
Identifies specific person/thing
e.g. Blood Type
e.g. fingerprint
Forensic Science: Fundamentals & Investigations, Chapter 2

11. Types of Evidence
Evidence taken from a crime scene. Direct or circumstantial evidence? Physical or biological evidence? Class or individual evidence? Explain why this would be or would not be trace evidence.
Forensic Science: Fundamentals & Investigations, Chapter 2

12. The Crime Scene Investigation Team
Who is at the crime scene?
Police and possibly a district attorney.
Crime scene investigators.
Medical examiners.
Detectives.
Specialists.
Forensic Science: Fundamentals & Investigations, Chapter 2

13. Types of Evidence
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14. Documents
Hand written
Type or Printed
Authenticity?
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15. Glass How broken? Link a suspect to a crime scene Fingerprints Blood
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16. Soils, Minerals, Wood, and Other Vegetative Matter.
Location
Link suspect
Trace Evidence
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17. Fingerprints
Mainstay of Forensics
Who is on file?
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18. Hair
What type?
How removed?
Match to a person
DNA
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19. Fibers
Link suspect to a location or victim
Origin?
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20. Firearms and Ammunition
Circumstances of discharge
Link to suspect
Link to weapon
Link to victim
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21. Powder Residue Evidence of shooting Circumstances of shooting
Type of weapon
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22. Explosives & Propellants
Link to suspect or victim
Origin
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23. Tool Marks
Match tool to scares
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24. Impressions
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26. Drugs
Type of Drug?
Strength?
Origin?
Legal?
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27. Paint
Origin
Match
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28. Blood, Semen, Saliva, Organs, & other Physiological Fluids
Origin
DNA
Condition
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30. Summary
Locard’s exchange principle: contact between people and objects can transfer material that can determine the nature and duration of the transfer.
Evidence can be direct, indirect (circumstantial), physical, biological, class, or individual.
A crime scene investigation team consists of police, detectives, crime scene investigators, medical investigators, and specialists.
Numerous types of evidence depending on the crime!
Forensic Science: Fundamentals & Investigations, Chapter 2