1. Unit 2: Evidence Please pick up Unit 2 Packet A!

2. 2 Unit 2 Evidence Targets- 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 summarize the seven steps of a crime-scene investigation sketch a crime scene to scale with measurements Distinguish between direct and indirect graphical relationships.

3. 3 Vocabulary 1. Arch- 2. Circumstantial evidence- 3. Class evidence- 4. Correlation- 5. Crime scene sketch- 6. Direct evidence- 7. Direct relationship- 8. Individual evidence- 9. Inverse relationship- 10. Locard’s principle- 11. Loop- 12. Outlier- 13. Trace evidence- 14. Whorl-

4. Forensic Science: Fundamentals & Investigations, Chapter 2 4 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: 1. When a person comes in contact with an object or another person, a cross-transfer of physical material can occur. 2. Study of the material can determine the nature and duration of the transfer.

5. Forensic Science: Fundamentals & Investigations, Chapter 2 5 Types of Evidence Direct evidence Testimony by a witness about what that witness saw, heard, or did

6. Forensic Science: Fundamentals & Investigations, Chapter 2 6 Types of Evidence Circumstantial evidence also called Indirect trace evidence Physical evidence e.g., fingerprints Biological evidence e.g., blood or hairs

7. Forensic Science: Fundamentals & Investigations, Chapter 2 7 Types of Evidence ClassIndividual Identifies group of person/things Identifies specific person/thing e.g. Blood Typee.g. fingerprint

8. Forensic Science: Fundamentals & Investigations, Chapter 2 8 Types of Evidence Explain why this would be or would not be trace evidence

9. Types of Evidence bsapp.com

10. Documents Hand written Type or Printed Authenticity? bsapp.com

11. Glass How it was broken? Link a suspect to a crime scene Fingerprints Blood bsapp.com

12. Soils, Minerals, Wood, and Other Vegetative Matter. Location Link suspect Trace Evidence bsapp.com

13. Fingerprints Mainstay of Forensics Who is on file? bsapp.com

14. Hair What type? How removed? Match to a person DNA bsapp.com

15. Fibers Link suspect to a location or victim Origin? bsapp.com

16. Firearms and Ammunition Circumstances of discharge Link to suspect Link to weapon Link to victim bsapp.com

17. Powder Residue Evidence of shooting Circumstances of shooting Type of weapon bsapp.com

18. Explosives & Propellants Link to suspect or victim Origin bsapp.com

19. Tool Marks Match tool to scars Match tool to scars bsapp.com

20. Impressions bsapp.com Location? Link to suspect or victim

21. Drugs Type of Drug? Strength? Origin? Legal? bsapp.com

22. Paint Origin Match bsapp.com

23. Blood, Semen, Saliva, Organs, & other Physiological Fluids Origin DNA Condition bsapp.com

24. Forensic Science: Fundamentals & Investigations, Chapter 2 24 The Seven S’s of Crime Scene Investigation 1. Secure the scene 2. Separate the witnesses 3. Scan the scene 4. Seeing the scene 5. Sketch the scene 6. Search for evidence 7. Secure the collected evidence

25. Forensic Science: Fundamentals & Investigations, Chapter 2 25 Crime-Scene Sketch Form

26. Forensic Science: Fundamentals & Investigations, Chapter 2 26 Crime-Scene Sketch Example

27. Forensic Science: Fundamentals & Investigations, Chapter 2 27 Analyze the Evidence Lab results can: o Show reliability of witness accounts o Establish the identity of suspects or victims o Show suspects to be innocent or link them with a scene or victim

28. Forensic Science: Fundamentals & Investigations, Chapter 2 28.............. Summary.................. Summary.... o Locard’s exchange principle: Contact between people and objects can transfer material that can determine the nature and duration of the transfer o Evidence can be direct or indirect Physical or biological traces o Investigations consist of recognizing, documenting, and collecting evidence.

29. Graph Relationships o When you look for patterns in the data that you have graphed o There are 2 different patterns you may find: direct inverse Forensic Science: Fundamentals & Investigations, Chapter 2 29

30. Direct relationship Relationship Statement: When the independent variable is at its highest, the dependent variable is at its highest Forensic Science: Fundamentals & Investigations, Chapter 2 30

31. Inverse Relationship Relationship Statement: When the independent variable is at its highest, the dependent variable is at its lowest

32. What if no relationship is shown? If the graph looks like  Relationship Statement: When the independent variable increases, the dependent variable doesn’t change

33. What if no relationship is shown? If the graph looks like  Relationship Statement: When the independent variable increases, the dependent variable does not change in a predictable way