1. Chapter 10: Crime Scene Investigation
Textbook page 167

2. I. Introduction A. Forensic science begins at the crime scene.
B. Four steps of Crime Scene Investigation (CSI)
Recognition—scene survey, documentation, collection
Identification—comparison testing
Individualization—evaluation, interpretation
Reconstruction—reporting and presentation

3. I. Introduction (cont.) VS.
C. A main goal of CSI is to successfully identify and preserve physical evidence.
1. Two general types of evidence: direct and physical
Direct/testimonial = evidence in the form of a statement made under oath.(go to eyewitness slides)
Physical evidence = any and all objects and materials that are relevant in a crime (examples: drugs, toxic substances, paints, gunshot residues, firearms and ammunition, impressions, petroleum products, blood, fibers, glass, hair, body fluids, fingerprints, etc.)
VS.

4. Direct/testimonial evidence extension activity 
Note: The next 10 slides came from The Science Spot website

5. What is testimonial evidence?
Testimonial evidence includes oral or written statements given to police as well as testimony in court by people who witnessed an event.
Eyewitness accounts can be a useful tool in helping investigators with analyzing a crime scene, but are not viewed to be highly reliable. In addition, eyewitness identifications (right or wrong) can have a big influence on the outcome of an investigation or trial.
People are likely to view the same scene in different ways depending on their positions, line of sight, familiarity with the area, and other factors that can interfere with a person’s ability to remember details.

6. Memory Challenge Directions:
You will have 30 seconds to view the next screen.
Try to memorize all 20 items you see!
You are NOT allowed to write anything down
You CANNOT talk to anyone else.

7. Items to remember ...
Neuroscience for Kids -

8. You have 2 minutes to list as many of the items as you can!
What do you remember?
You have 2 minutes to list as many of the items as you can!
How did you do?
All 20 – Awesome
15-19 – Great
10-14 – Pretty swell
5-9 – Could be better
4 or Less – Wake up
Teacher Note: Try to influence the students’ memory of the items. As they are writing down the items they remember, suggest two or three items that were not shown, such as a banana (on the info slide), a nail (goes with hammer), or pen (instead of the pencil). As you go over the correct items, ask the students if they added any of the ones you told them to remember. Tie this into the discussion (next slide) on how a person’s memory can be affected by another person.

9. Did you know?
According to The Innocence Project (2008) "Eyewitness misidentification is the single greatest cause of wrongful convictions nationwide, playing a role in more than 75% of convictions overturned through DNA testing." Still, the criminal justice system profoundly relies on eyewitness identification and testimony for investigating and prosecuting crimes (Wells & Olson, 2003).
What factors affect a person’s memory and their ability to identify a suspect?
Source:

10. Witness Factors
Age may play a role in the accuracy of an eyewitness’ statement or identification of a suspect. Studies have shown that when a lineup contains the actual culprit, both young children and elderly perform well, but when the lineup does not contain the culprit there is a higher rate of mistaken identifications.
The race of the witness may also play a role. The Cross Race Effect (CRE) is a phenomenon in which people are better at recognizing faces of their own race rather than those of other races.
The use of drugs can alter a person’s ability to recall the events of a crime even after they are no longer under the influence.
A person’s memory of an event can be influenced by other witnesses, investigators, and/or the media. Investigators use open-ended questioning and follow procedures for conducting line-ups to limit their influence on a witness’ memory of an event or identification of a suspect.
Source:

11. Crime Scene & Suspect Factors
A crime that is extremely traumatic for an eyewitness may affect his/her recall of the event. For example, a witness confronted with a weapon tends to focus on the weapon rather than the perpetrator’s face.
Someone who is able to focus on a perpetrator's face for a minute or longer will tend to have a more accurate memory than someone who saw the person for only a few seconds.
Studies have shown that faces that are either highly attractive, highly unattractive, or distinctive are more likely to be accurately recognized. Simple disguises, such as hats or sunglasses, can interfere with accurate eyewitness identification. However, body piercings and tattoos increases the likelihood of an accurate identification.
The time of day in which the crime occurred as well as a person’s view of the scene may affect what a he/she is able to see. In addition, a person who is familiar with the area in which the crime took place, may have a better recall of the positions of the victims or suspects.
Source:

12. Crime Scene Challenge
Now that your eyes and brain are warmed up, let’s test your observation skills a bit more.
You will have 2 minutes to study the photograph of a crime scene on the next slide.
Try to pay attention to details as you will be asked 10 questions about the crime scene!
You are not allowed to write anything down until after the time is up.
Ready?

14. Answer each question below.
1. What color coffee mug was in the picture? Blue Red Yellow
2. When was the deadline? Yesterday Today Tomorrow
3. What time was on the clock on the wall? : : :55
4. How many sticky notes were on the whiteboard? Four Six Eight
5. Which of the following was NOT in the picture? Stapler Trash Can Printer
6. What was the name on the plaque on the desk? Bill Brian Carl
7. What color was the victim's shirt? Black Blue Red
8. How many plants were in the picture? None One Two
9. What was the color of the marker in the desk drawer? Red Blue Green
10. Where was the book in the picture? On a box In the trash can Under the body
Source:

15. 2. Use of physical evidence
Prove that a crime has been committed
Corroborate testimony
Link a suspect with a victim or with a crime scene
Establish the identity of persons associated with a crime
Allow reconstruction of events of a crime

16. II. Defining a crime scene
Crime scene are diverse and unique . . .
no two scenes are exactly the same

17. II. Defining a crime scene (cont.)
Note: Each crime scene can be a combination of these classifications. Also as an investigation proceeds, the definition of the crime scene can be constantly modified.
II. Defining a crime scene (cont.)
Classification of crime scenes can be based on . . .
location
primary: site of original or first criminal activity
secondary: any subsequent sites of criminal activity
size
macroscopic crime scene: composed of many crime scenes (overall area)
microscopic crime scene: focused on specific types of physical evidence found at the macroscopic crime scene
type of crime committed
homicide
robbery
sexual assault
etc.
condition of the crime scene
organized
disorganized
physical location of crime scene
indoors
outdoors
vehicle
etc.
others

18. III. General procedures for CSI (recognition step)
Secure and protect the crime scene
First responding officer
critical role
responsibilities include:
assist the victim
search for and arrest suspects if possible
detain all witnesses
protect and secure the scene
note and communicate to investigators all movements and alterations made to the scene

19. III. General procedures for CSI A
III. General procedures for CSI A. Secure and protect the crime scene (cont.)
Establish crime scene security
Why? Locard’s Principle
Multi-level approach
James, S.H., & Nordby, J.J. (2005). Forensic Science: An Introduction to Scientific and Investigative Techniques. 2nd Edition. New York: Taylor & Francis. Pg. 171.

20. III. General procedures for CSI (cont.)
Survey the scene
“Walk-through”
Note: transient (temporary) or conditional (the result of an action) evidence, points of entry and exit, and initial observations
Documenting a crime scene
Four main components = notes, photography, videotape, sketch
(see concept map or web for explanations)

21. III. General procedures for CSI (cont.)
Crime Scene Searches
Preliminary search
done once the scene is secured
purpose = note obvious evidence
Post-documentation search
intensive search for less obvious/overlook evidence
completed before collection and packaging of evidence
evidence found must be documented before collection

22. III. General procedures for CSI D. Crime Scene Searches (cont.)
Search methods/patterns
Purpose = provide systematic search so no evidence missed
Organized = everyone on same page and stress no touching or altering evidence (just mark they are there)
Six most common search patterns
Link
Line or Strip
Grid
Wheel or Ray
Spiral
Zone

23. Crime scene search patterns
4. Wheel or Ray
1. Link
5. Spiral
2. Line or strip
6. Zone
1 2
3 4
3. Grid

24. III. General procedures for CSI (cont.)
Collection of Evidence
Done AFTER crime scene documentation and intensive search for evidence
Evidence collector = one person given this job
--Why?
To ensure evidence collected, packaged, marked,
sealed, and preserved in CONSISTENT manner
Order of collection
no set order
depends on nature of the evidence
--example: transient, fragile, or easily lost evidence collected first
IMPORTANT: if any new evidence discovered, must first DOCUMENT it before collecting

25. III. General procedures for CSI E. Collection of Evidence (cont.)
General collection guidelines
Most items packaged in primary container, then placed inside secondary container
Outer container
completely sealed at time of collection with tamper-resistant tape
marked with: items contained; ID of collector; time, date, and location of collection
Each item packaged SEPARATELY to prevent
cross-contamination

26. III. General procedures for CSI E. Collection of Evidence (cont.)
Ways to package different categories of evidence
Biological material
--packaged in a dry paper bag (NOT plastic)
Trace evidence (hairs, fibers, etc.)
--packaged in small envelops or tins
--Druggist’s folds used as primary container =
pieces of paper folded around items to hold trace
evidence in place before placed in outer container
Fingerprints
--lifted fingerprints are attached to an index card
Arson debris
-- packaged in old paint cans or mason jars (sealed
glass jar)
Castings
--packaged in a box with cushioning

27. III. General procedures for CSI (cont.)
Crime Scene Reconstruction
The process of analyzing data to ultimately develop a theory of the crime
Stages involved (see diagram and explanations on page 180 of textbook):
Data collection
Conjecture
Hypothesis formation
Testing
Theory formation

28. Crime Scene sketching
methods
Crime scene sketching
example
Crime scene sketching
directions

29. Crime Scene Sketching
CS sketching is the final step in CS documentation
Provides for dimensional relationships
2 views
Bird’s eye view (top-down/overhead . . .most common)
Elevation view (side-on)
2 types
Rough sketch—completed at scene, not to scale
Final sketch—completed later with lots of time and detail, drawn to scale

30. 4 techniques for measuring evidence
Triangulation (indoor) RP RP RP
evidence
evidence
Rectangular coordinates (indoor)
Baseline (outdoor)
evidence RP RP
evidence
evidence
evidence
Polar coordinates (outdoor)

31. CS Sketching Lab Tips Label North Label RP
Use rectangular coordinates to measure evidence
Symbols
Evidence in final sketch:
Draw in body only, for all others use LETTERS
Measure to center of object
Do not include evidence measurements in sketch, they will be in your evidence table
Use RULER in final sketch and tables
Final sketch drawn to SCALE (include key to scale)
Evidence table
Use detail when including item description (ie. Book What book? Size?—measure dimensions)
door
window
Letter
Item/description
Location
From N From W A B C
Body

32. CS Sketch Example
= 1foot