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
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
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Forensic Science: Fundamentals & Investigations, Chapter 2

2. -Paul Kirk on the __________ ____________ ___________
“Wherever he steps, whatever he touches, whatever he leaves, even unconsciously, will serve as a silent witness against him. Not only his fingerprints or his footprints, but his hair, the fibers from his clothes, the glass he breaks, the tool mark he leaves, the paint he scratches, the blood or semen he deposits or collects. All of these and more, bear mute witness against him. This is evidence that does not forget. It is not confused by the excitement of the moment. It is not absent because human witnesses are. It is factual evidence. Physical evidence cannot be wrong, it cannot perjure itself, it cannot be wholly absent. Only human failure to find it, study and understand it, can diminish its value.”
-Paul Kirk on the __________ ____________ ___________
Forensic Science: Fundamentals & Investigations, Chapter 2

3. ______________ _____ ___________________
Dr. __________ _________, director of the world’s first forensic lab (1910, Lyon, France), established the idea of the ________________; 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 _______ and _________ of the transfer.
Forensic Science: Fundamentals & Investigations, Chapter 2

4. Types of Evidence _________ _________ _____________ For example:
_________ _________
_____________
For example:
Forensic Science: Fundamentals & Investigations, Chapter 2

5. Types of Evidence _____________ evidence _________ evidence
also called _________
trace evidence
_________ evidence
e.g., _________
e.g., _______ __ ______
Forensic Science: Fundamentals & Investigations, Chapter 2

6. What is________ ___________?
________________________________________________________________________
Forensic Science: Fundamentals & Investigations, Chapter 2

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

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

9. The Seven S’s of Crime Scene Investigation
_______the scene.
_______ the witnesses.
____ the scene.
____ to it that the crime scene examiners receive overall and close up photos with and without measuring rulers.
________ the scene.
________ for evidence.
________ the collected evidence.
Forensic Science: Fundamentals & Investigations, Chapter 2

10. The Crime Scene Investigation Personnel
Who is at the crime scene?
_______________________
Forensic Science: Fundamentals & Investigations, Chapter 2

11. ________________________
A ________
D ________
P ________
T ________
Forensic Science: Fundamentals & Investigations, Chapter 2

12. Secure the Crime Scene Look for signs of life
Cordon off the scene (only allow authorized personnel in)
Bodies should be certified as “dead” by a ________________ before being moved
Forensic Science: Fundamentals & Investigations, Chapter 2

13. Scanning the Scene
The forensic examiners need to scan the scene to determine where photos should be taken. A determination may be made of a _________ ________ _______and ____________ ________ ________ and priorities assigned regarding examination.
A walkthrough is performed by the crime scene investigator, the first officer, and sometimes the lead detective
Record initial observations of who, what, where, when, and how
Make a plan of action
Forensic Science: Fundamentals & Investigations, Chapter 2

14. Seeing the Scene ____________ is in charge of this and documenting.
How do they document? 1. 2. 3. 4.
Forensic Science: Fundamentals & Investigations, Chapter 2

15. Record the crime scene and potential evidence
Notes – record the following while at the crime scene (details are the key)
a. Date
b. Time
c. Description of the location, weather, and environmental conditions
d. Description of the crime
e. Location of the evidence relative to other key points
f. Names of all people involved
g. Any other relevant information
Forensic Science: Fundamentals & Investigations, Chapter 2

16. Photography Nothing should be moved until photographed
Take photos of the scene and the surroundings
Photograph _______ and ______. What else?
Use wide and close-up photos
Use various angles of each piece of evidence
Use a _____ to show size
Forensic Science: Fundamentals & Investigations, Chapter 2

17. Sketches
Draw a rough sketch at the scene (reconstruct a better one later) including
a. Date, time, and location
b. Recovered items
c. Important features
d. Accurate distance measurements of objects (from two fixed points) ___________________
e. _________ -f.__________ -g.__________
Forensic Science: Fundamentals & Investigations, Chapter 2

18. Crime-Scene Sketch Form
Note:
Position of the body
All objects should be measured from two immovable objects
Doors/windows
Other evidence
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19. Forensic Science: Fundamentals & Investigations, Chapter 2

20. Measuring Techniques 1. _______________________
2. _______________________
3. _______________________
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21. _____________ Method
For each piece of evidence being recorded, _________________________________ as reference points that are not likely to _______.
The two reference points and the piece of evidence form a triangle, hence the term triangulation
Whatever object you are measuring to or from, use the same spot on the object every time
Forensic Science: Fundamentals & Investigations, Chapter 2

22. Baseline Method ____________ but _____________
2. Using a straight line between two known points, items are measured along the line and then measured perpendicular to the line
3. Inside or outside of a house, this line can be a straight wall
4. For outdoor scenes, use a string or a long measuring tape as the reference or baseline
Forensic Science: Fundamentals & Investigations, Chapter 2

23. Why Isn’t This Method as Accurate
As the distance between the baseline and the objects being measured increases, so does _______.
When is it
recommended?
Forensic Science: Fundamentals & Investigations, Chapter 2

24. _______ Method Typically ________________.
To establish the position of an object in a room, measurements are taken from two different walls within the room that are perpendicular to one another. The tape measure is held perpendicular to the wall when the measurement is taken to ensure 90 degree angles from the wall to the object being measured.
Forensic Science: Fundamentals & Investigations, Chapter 2

25. Forensic Science: Fundamentals & Investigations, Chapter 2

26. Videography a. ________ the video b. Be _________
c. Record from different _________
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27. Collect and Package Evidence
A. Physical evidence must be packaged and collected before time and weather can alter it
B. Physical Evidence can serve as ________ _________
C. The Golden Hour – the window of opportunity to collect time-sensitive information or evidence ex. Cctv; witnesses
D. Each item must be placed in a separate container, and sealed and labeled.
E. The most fragile evidence is collected and packaged first
F. Different types of evidence require specific or special collection and packaging techniques
Forensic Science: Fundamentals & Investigations, Chapter 2

28. Securing and Collecting Evidence
All evidence needs to be properly packaged, sealed, and labeled. Specific procedures and techniques for evidence collection and storage must be followed.
___________- stored in airtight, unbreakable containers.
___________- is stored in breathable containers so the evidence can dry out, reducing the chance of mold contamination. After the evidence is allowed to air dry, it is packaged in a ______ _____
Forensic Science: Fundamentals & Investigations, Chapter 2

29. Securing and Collecting Evidence cont.
An evidence log and a ________ ____ _________ document must be attached to the evidence container.
Forensic Science: Fundamentals & Investigations, Chapter 2

30. Chain of Custody
Chronological documentation that records the sequence of control and transfer of evidence.
In order to present credible evidence in court, a chain of custody log is essential.
A person bags the evidence, marks it for identification, seals it, and signs it across the sealed edge (above, left).
It is signed over to a technician in a lab for analysis who opens it, but not on the sealed edge.
After analysis, the technician puts it back in the evidence bag, seals it in another bag, and signs the evidence log (above, right).
Forensic Science: Fundamentals & Investigations, Chapter 2

31. Analyze the Evidence
The facts of the case are determined when the forensic lab processes all the collected evidence.
The lab then sends the results to the lead detective who aims to see how it all fits into the crime scenario.
Forensic Science: Fundamentals & Investigations, Chapter 2

32. Analyze the Evidence The lab results can:
Show how reliable are any witness accounts.
Establish the identity of suspects or victims.
Show suspects to be innocent or link them with a scene or victim. (alibi)
Forensic Science: Fundamentals & Investigations, Chapter 2

33. Crime Scene Reconstruction
Crime scene reconstruction involves:
forming a hypothesis of the sequence of events from before the crime was committed through its commission (authorization of production).
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34. Staged Crime Scenes
When the lab results do not match up with the testimony of witnesses, it can mean the crime was staged; common examples include:
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

35. How Can You Tell? ____________________________
_______________________________
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36. Staged Crime Scenes
To help determine whether a crime scene was staged, consider:
Whether the type of wound found on the victim matches the weapon employed.
Whether the wound could have been easily self-inflicted.
The mood and actions of the victim before the event.
The mood and actions of a suspect before the event.
Forensic Science: Fundamentals & Investigations, Chapter 2

37. 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.
The investigation consists of recognizing, documenting, and collecting evidence.
Forensic Science: Fundamentals & Investigations, Chapter 2

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