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Forensic Science: Fundamentals & Investigations, Chapter 2 1
Crime Scene Investigation and Evidence Collection
o Identify the type of professionals who are present at a crime scene
o Describe how evidence from a crime scene is analyzed
o Summarize Locard’s exchange principle o Identify four examples of trace evidence o Distinguish between direct and circumstantial
evidence All Rights Reserved South-Western / Cengage Learning © 2012, 2009
Crime Scene Investigation and Evidence Collection
o Summarize the three steps of a crime scene investigation
o Explain the importance of securing the crime scene
o Identify the methods by which a crime scene is documented
o Demonstrate proper technique in collecting and packaging trace evidence
Wednesday 9/26 D dayWednesday 9/26 D day
AIM: EVIDENCE
DO NOW:
Designate each person at your table a role:
2 people – director
2 people – reporter
1 person – recorder
* Brainstorm different types of physical evidence used to help solve crimes
AIM: EVIDENCE
Read Lessons from the JONBENET RAMSET case - to be collected ( 1 per table )
Answer the following questions with your table:
1. What mistakes were made by the Boulder Police Department in securing the crime scene?
2. What specific kinds of evidence may have been compromised?
3. What could the police have done differently to secure the crime scene and the evidence?
Principle of ExchangePrinciple of Exchange
Established by Dr. Edmond Locard, the principle states:
o When a person comes in contact with an object or another person, a cross-transfer of physical material can occur
o Study of the material can determine the nature and duration of the transfer
Types of Evidence Types of Evidence
Direct evidence
Testimony by a witness about what that witness saw,
heard, or did
Types of Evidence Types of Evidence
Circumstantial evidence
• also called Indirect
• trace evidence
Physical evidence
• e.g., fingerprints
Biological evidence
• e.g., blood or hairs
Types of EvidenceTypes of Evidence
Explain why this would be or would not be trace evidence
Wednesday 9/26 D day HOMEWORK Wednesday 9/26 D day HOMEWORK
Read pg. 23Write a paragraph explaining the difference between
class and individual evidence. Make sure to give examples of each
Include the following questions in your discussion- Would class or individual evidence be considered
direct or circumstantial- If evidence is circumstantial, would you classify
class or individual evidence as physical or biological?
Thursday 9/27 E dayThursday 9/27 E dayAIM: EVIDENCE
DO NOW: Have HW out on your tableRead article on Natalee Halloway What happened to Natalee Holloway in Aruba in 2005? This is an
unsolved case in which questions have been raised about why crime scene investigators have not been able to find her body. In fact, investigators searched the island with an array of cutting-edge tools, from a remote-controlled submersible equipped with a video camera and sonar used for probing the water under bridges and in lagoons, to telescoping rods tipped with infrared sensors and cameras used for looking beneath manhole covers and into shadowy caverns.
Read the articles and make your own investigation by reading the primary
sources.
How would you decide?
Thursday 9/27 E dayThursday 9/27 E day
AIM: EVIDENCE
DO NOW: Have HW out on your table
Answer the following questions individually: o Summarize Locard’s exchange principle o Identify four examples of trace evidence o Distinguish between direct and circumstantial
evidence
.
The Crime Scene The Crime Scene Investigation Team Investigation Team
Who is at the crime scene?
o Policeo District attorney (possibly)o Crime scene investigatorso Medical examinerso Detectiveso Specialists
The Seven The Seven SS’s of Crime Scene ’s of Crime Scene Investigation Investigation
1. Secure the scene (first responder police officer)
2. Separate the witnesses -Witnesses must not be allowed to talk to each other. Their accounts of the events will be compared
3. Scan the scene - The forensic examiners need to scan the scene to determine where photos should be taken. A determination may be made of a primary crime scene and secondary crime scene and priorities assigned regarding examination.
The Seven The Seven SS’s of Crime Scene ’s of Crime Scene Investigation Investigation
4. Seeing the scene - Photos of the overall area and close-up photos with and without a measuring ruler should be taken.
5. Sketch the scene - An accurate rough sketch of the crime scene is made, noting the position of the body (if any) and any other evidence. (see crime scene sketch)
6. Search for evidence - Depending on the number
of investigators, a spiral, grid, linear, or quadrant pattern should be walked and location of evidence marked, photographed, and sketched (see crime scene search patterns
7. Secure the collected evidence - All evidence needs to be properly packaged, sealed, and labeled
Crime-Scene Sketch Form
Crime-Scene Search Patterns
Packaging the evidence
1. Crease a clean paper and place evidence in the X position
2. Fold in the left and right sides, and then fold in the top and bottom
3. Put the bindle into a plastic or paper evidence bag affixing a seal over the opening
4. Write your name on the seal
Evidence ID Forms
Chain of Custody
Maintaining a chain of custody log is essential to present credible evidence in court
Chain of Custody (cont’d.)
1. Bag the evidenceAdd identification Seal itSign it across the sealed edge
2. Sign over to a lab technician Open bag on non-sealed edge
3. Return items to the evidence bagSeal evidence bag in another bagSign the evidence log
Friday 9/28 F dayFriday 9/28 F day
AIM: EVIDENCE
DO NOW:
Answer the following questions individually: o Identify the type of professionals who are present at a
crime sceneo Describe how evidence from a crime scene is analyzed o Explain the importance of securing the crime scene
.
Analyze the EvidenceAnalyze the Evidence
o Facts result from collected evidence processed by the forensic lab
o Lead detective aims to see how facts fit into the crime scenario
Analyze the EvidenceAnalyze the Evidence
Lab results can: o Show reliability of witness accountso Establish the identity of suspects or victimso Show suspects to be innocent or link them
with a scene or victim
Crime Scene Reconstruction Crime Scene Reconstruction
Crime scene reconstruction involves: o Forming a hypothesis of the sequence of
events o From before the crime was committed
through its commission
Staged Crime Scenes Staged Crime Scenes
When lab results don’t match up with the testimony of witnesses
Common examples:
o Staging a fire—to cover bankruptcyo Staging a suicide—to cover a murdero Staging a burglary—to collect insurance
money
Staged Crime ScenesStaged Crime Scenes
Was the crime scene staged? Consider:
o Does the type of wound match the weapon?o Could the wound be easily self-inflicted? o What were the mood and actions of the victim
before the event?o What were the mood and actions of the suspect
before the event?
. . . . . . . . . . . . . . . . . . . . . . . . . . . . SummarySummary . . . . . . . .
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 A crime scene investigation team consists of police, detectives, crime scene investigators, medical investigators, and specialists.
. . . . . . . . . . . . . . . . . Summary. . . . . . . . . . . . . . . . . Summary
o Investigations consist of recognizing, documenting, and collecting evidence.
o First responding officers identify the extent of the crime scene, secure it, and segregate witnesses.
o Crime scene investigators document the crime scene.
o Evidence is collected, packaged, and labeled.o The evidence is analyzed and interpreted to fit the
crime scenario.
Conclusion HWConclusion HW
Write an essay discussing the following questions – individually
If an eyewitness to a crime is a relative, friend, or acquaintance of the person committing the crime would he or she be a more or less reliable witness? Why or why not?
Wednesday 10/3 B dayWednesday 10/3 B day
AIM: EVIDENCE
DO NOW: 1. Have HW out on your desk (put into a pile by sink)
2. Re-read The Atlanta Child Murders Case
You are going to become the defense attorney for Wayne Williams.
What would your strategy be to create reasonable doubt and allow the jury to find Mr. Williams innocent?
Forensic Science: Fundamentals & Investigations, Chapter 2 31
Forensic Science: Fundamentals & Investigations, Chapter 2 32