1. 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
Describe how evidence from a crime scene is analyzed
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Forensic Science: Fundamentals & Investigations, Chapter 2

2. Chapter 2 Crime Scene Investigation and Evidence Collection By the end of this chapter you will be able to:
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
Forensic Science: Fundamentals & Investigations, Chapter 2

3. Principle of Exchange
Established by Dr. Edmond Locard, the principle states:
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

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

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

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

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

8. The Seven S’s of Crime Scene Investigation
Secure the scene
Separate the witnesses
Scan the scene
Seeing the scene
Sketch the scene
Search for evidence
Secure the collected evidence
Forensic Science: Fundamentals & Investigations, Chapter 2

9. Do Now: On a clean piece of paper and using your Crime scenes ONLY:
Identify the Seven S’s.
Summarize the most important part for each step
Forensic Science: Fundamentals & Investigations, Chapter 2

10. The Seven S’s of Crime Scene Investigation
Secure the scene
1st responder, ensure CS Integrity, keep log of who enters/exits, secures area.
Separate the witnesses
Who called, what did you see, when did it occur, who is the victim/perpetrator, .
Scan the scene
Establish 1o and 2o Cs
Forensic Science: Fundamentals & Investigations, Chapter 2

11. The Seven S’s of Crime Scene Investigation
4. Seeing the scene
Photograph, close ups w/o scale, many angles
Sketch the scene
Triangulated measurements, labels, scale, doors, windows, position on victim,vehicles, compass heading
Search for evidence
Using 1 of 4 patterns
7. Secure the collected evidence
Forensic Science: Fundamentals & Investigations, Chapter 2

12. Systematic searches
Need to be done so that no accusations of a cover up arise or overlook of evidence
Need one person in control to coordinate collection of evidence
Four main types
Spiral
Strip or Line
Grid
quadrant

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

14. Crime-Scene Search Patterns
Forensic Science: Fundamentals & Investigations, Chapter 2

15. Packaging the evidence
Crease a clean paper and place evidence in the X position
Fold in the left and right sides, and then fold in the top and bottom
Put the bindle into a plastic or paper evidence bag affixing a seal over the opening
Write your name on the seal
Forensic Science: Fundamentals & Investigations, Chapter 2

16. Evidence ID Forms
Forensic Science: Fundamentals & Investigations, Chapter 2

17. Chain of Custody
Maintaining a chain of custody log is essential to present credible evidence in court
Forensic Science: Fundamentals & Investigations, Chapter 2

18. Chain of Custody (cont’d.)
Bag the evidence Add identification Seal it Sign it across the sealed edge
Sign over to a lab technician Open bag on non-sealed edge
Return items to the evidence bag Seal evidence bag in another bag Sign the evidence log
Forensic Science: Fundamentals & Investigations, Chapter 2

19. Analyze the Evidence
Facts result from collected evidence processed by the forensic lab
Lead detective aims to see how facts fit into the crime scenario
Forensic Science: Fundamentals & Investigations, Chapter 2

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

21. Crime Scene Reconstruction
Crime scene reconstruction involves:
Forming a hypothesis of the sequence of events
From before the crime was committed through its commission
Forensic Science: Fundamentals & Investigations, Chapter 2

22. Staged Crime Scenes
When lab results don’t match up with the testimony of witnesses
Common examples:
Staging a fire—to cover bankruptcy
Staging a suicide—to cover a murder
Staging a burglary—to collect insurance money
Forensic Science: Fundamentals & Investigations, Chapter 2

23. Staged Crime Scenes Was the crime scene staged? Consider:
Does the type of wound match the weapon?
Could the wound be easily self-inflicted?
What were the mood and actions of the victim before the event?
What were the mood and actions of the suspect before the event?
Forensic Science: Fundamentals & Investigations, Chapter 2

24. 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 or indirect
Physical or biological traces
A crime scene investigation team consists of police, detectives, crime scene investigators, medical investigators, and specialists.
Forensic Science: Fundamentals & Investigations, Chapter 2

25. Summary
Investigations consist of recognizing, documenting, and collecting evidence.
First responding officers identify the extent of the crime scene, secure it, and segregate witnesses.
Crime scene investigators document the crime scene.
Evidence is collected, packaged, and labeled.
The evidence is analyzed and interpreted to fit the crime scenario.
Forensic Science: Fundamentals & Investigations, Chapter 2

26. Introduction—Vocabulary
chain of custody - a list of all people who came into contact with an item of evidence
class characteristics - properties of evidence that can be associated only with a group and never a single source
Frye Standard - rule of admissibility of evidence; evidence, procedures, and equipment presented at trial must be generally accepted by the relevant scientific community
individual characteristics - properties of evidence that can be attributed to a common source with an extremely high degree of certainty
Forensic Science II: Overview of Forensics, Chapter 1
© 2012 Cengage Learning. All Rights Reserved

27. Introduction—Vocabulary
Locard’s exchange principle - when two objects come into contact with one another, a cross-transfer of materials occurs
physical evidence - any object that can establish that a crime has been committed or can link a suspect to a victim or crime scene
reference sample - a sample from a known source used for comparison, also referred to as exemplar
scientific method - a series of logical steps to ensure careful and systematic collection, identification, organization, and analysis of information
Forensic Science II: Overview of Forensics, Chapter 1
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28. Murders at the Mansion
The Menendez brothers - Lyle (21) and Erik (18)
August — the brothers’ story is that they went out for the evening
The brothers call 911 at 11:47 to report the murder of their parents
After paying debts, there’s a $2 million estate
By end of year, the brothers spent half of the estate
Arrested in March 1990; indicted on Dec 8, 1992
Defense admits brothers killed their parents, but claims sexual, physical, and emotional abuse 28
Forensic Science II: Overview of Forensics, Chapter 1
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Forensic Science II: Title, Chapter #

29. Historical Development (Obj 1.2)
Alphonse Bertillon (1853–1914) — developed the first method of criminal identification
Sir Edward Richard Henry (1850–1931) — developed a fingerprint identification system that categorized fingerprints by whorl, loop, or arch pattern
Karl Landsteiner (1868–1943 — discovered blood groups
Edmond Locard (1877–1966) — founder of the Institute of Criminalistics at the University of Lyon in Lyon, France
Forensic Science II: Overview of Forensics, Chapter 1
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30. Historical Development (Obj 1.2)
Calvin Goddard (1891–1955) — invented the comparison microscope
Rosalind Franklin (1920–1958) — studied the molecule’s structure using X-ray diffraction photography of DNA
James Watson (1928– ) and Francis Crick (1916–2004) — using Franklin’s photography, constructed a structural model of DNA
Alec Jeffreys (1950– ) — invented DNA fingerprinting
Forensic Science II: Overview of Forensics, Chapter 1
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31. A Multidisciplinary Approach (Obj 1.3)
Examples:
Forensic nurse
Forensic chemist
Forensic toxicologist
Forensic meteorologist
Forensic accountant
Forensic Science II: Overview of Forensics, Chapter 1
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32. The Scientific Method (Obj 1.4)

33. The CSI Team and Crime Labs (Obj 1.5, 1.6, 1.7)
The crime-scene investigation team is a team of legal and scientific experts who work together to process a crime scene and evaluate the evidence
Forensic Science II: Overview of Forensics, Chapter 1
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34. The CSI Team and Crime Labs (Obj 1.5, 1.6, 1.7)

35. Evidence Chain of Custody
Provides documentation of every person who has come into contact with the evidence
A paper trail
Demonstrates to the courts that the evidence that is being presented at trial is free of contamination, alteration, or substitution
Forensic Science II: Overview of Forensics, Chapter 1
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36. The CSI Team and Crime Labs (Obj 1.5, 1.6, 1.7)
Processing a Crime Scene
Investigators choose the search method based on the size and location of the crime scene
Zone: building or other structure—homicide, home invasion, robbery, sexual assault, etc.
Spiral: large area, no barriers—open field—kidnapping, homicide
Line search: large area looking for a large object in a single direction—site of a plane crash
Grid: large area looking for a large object in two directions—arson investigation
Forensic Science II: Overview of Forensics, Chapter 1
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37. The CSI Team and Crime Labs (Obj 1.5, 1.6, 1.7)
Testimonial evidence — the witness testimony used to build a timeline of events
Physical evidence —any material collected or observed at a crime scene that could link potential suspects to a crime
What is Chain of Custody?
Forensic Science II: Overview of Forensics, Chapter 1
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38. Evidence Trace Evidence Reference samples Class characteristics
Individual characteristics
Forensic Science II: Overview of Forensics, Chapter 1
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39. Evidence Forensic Science II: Overview of Forensics, Chapter 1
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40. Landmark Cases (Obj 1.8) Frye v. United States (1923)
The Frye Standard — evidence, procedures, and equipment presented at trial must be generally accepted by the scientific community
Forensic Science II: Overview of Forensics, Chapter 1
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41. Landmark Cases (Obj 1.8) Daubert v Merrell Dow Pharmaceuticals (1993)
U.S. Supreme Court ruled that the trial judge had ultimate decision-making power regarding expert testimony at trial
1. Has it been tested?
2. Has it been peer reviewed?
3. What is the rate of error?
4. Is it generally accepted?
Forensic Science II: Overview of Forensics, Chapter 1
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42. Landmark Cases (Obj 1.8)
Forensic Science II: Overview of Forensics, Chapter 1
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43. Landmark Cases (Obj 1.8) Dr. Carl Coppolino (1963) The court ruled
The fact that a technique, test, or procedure is new does not necessarily mean its findings are inadmissible in court
The expert witness is responsible for providing scientifically valid testimony to support the findings
Forensic Science II: Overview of Forensics, Chapter 1
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44. The Judicial Process (Obj 1.9)
The U.S. Constitution (1787)
The Bill of Rights (1789)
The first ten amendments to the constitution
Sixth amendment ensures that a person will be tried by an impartial jury of his or her peers
Forensic Science II: Overview of Forensics, Chapter 1
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45. The Judicial Process (Obj 1.9)
Arrest - gathering evidence to show probable cause
Observation
Expertise
Information
Circumstantial evidence
Before the Trial — the discovery phase
At the Trial — prosecution and defense present their cases
Forensic Science II: Overview of Forensics, Chapter 1
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46. Forensic Science II: Overview of Forensics, Chapter 1
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47. Chapter Summary Forensic science is the application of science to law.
Many disciplines are utilized in forensic science.
Processing a crime scene requires a thorough and systematic approach.
Physical evidence is any substance that can link a potential suspect to a victim or crime
Forensic Science II: Overview of Forensics, Chapter 1
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48. Chapter Summary
When processing evidence, investigators use identification and comparison tests to attempt to make connections between victims, suspects, and crime scenes.
Evidence that possesses class characteristics can be associated with a group rather than with a specific individual.
Evidence that possesses individual characteristics can be associated with a single person with a high degree of certainty.
Forensic Science II: Overview of Forensics, Chapter 1
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49. Chapter Summary
A chain of custody is necessary to maintain the integrity of the evidence.
The judicial process in the United States is based on the U.S. Constitution.
Law enforcement personnel must prove probable cause before a judge will sign a search or arrest warrant.
In court, a jury of the suspect’s peers hears evidence from both sides.
Forensic Science II: Overview of Forensics, Chapter 1
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