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