Textbook page 167
I. Introduction
A. Forensic science begins at the crime scene.
B. Four steps of Crime Scene Investigation (CSI)
1. Recognition—scene survey, documentation,
collection
2. Identification—comparison testing
3. Individualization—evaluation, interpretation
4. Reconstruction—reporting and presentation
I. Introduction (cont.)
C. A main goal of CSI is to successfully identify and
preserve physical evidence.
1. Two general types of evidence: direct and
physical
a. Direct/testimonial = evidence in the form of a
statement made under oath.(go to eyewitness slides)
b. Physical evidence = any and all objects and
VS.
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.)
Direct/testimonial evidence
extension activity 
• Note: The next 10 slides came from The
Science Spot website
• http://sciencespot.net/Pages/classforsci.html#crimescene
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.
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.
Items to remember ...
Neuroscience for Kids - http://faculty.washington.edu/chudler/puzmatch1.html
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
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: http://www.helium.com/items/1276135-accurate-eyewitness-accounts
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: http://www.helium.com/items/1276135-accurate-eyewitness-accounts
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: http://www.helium.com/items/1276135-accurate-eyewitness-accounts
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?
Answer each question below.
1. What color coffee mug was in the picture?
2. When was the deadline?
Yesterday
Blue
Red
Today
3. What time was on the clock on the wall?
Tomorrow
10:40
11:05
4. How many sticky notes were on the whiteboard?
Four
7. What color was the victim's shirt?
Black
8. How many plants were in the picture?
None
Bill
Blue
10. Where was the book in the picture? On a box
Source: http://forensics.rice.edu/html/picture_begin.html
Eight
Trash Can
Brian
Printer
Carl
Red
One
9. What was the color of the marker in the desk drawer?
1:55
Six
5. Which of the following was NOT in the picture? Stapler
6. What was the name on the plaque on the desk?
Yellow
Two
Red
In the trash can
Blue
Green
Under the body
2. Use of physical evidence
a. Prove that a crime has been committed
b. Corroborate testimony
c. Link a suspect with a victim or with a crime
scene
d. Establish the identity of persons associated
with a crime
e. Allow reconstruction of events of a crime
II. Defining a crime scene
A. Crime scene are diverse and unique . . .
no two scenes are exactly the same
http://www.exposay.com/celebrity-photos/crime-scene-4th-shooting-inhacney-within-2-weeks-1uvxtj.jpg
http://www.srpublications.com/criminology/item/D/images_D/crime_s
cene_reconstruction.jpg
II. Defining a crime scene (cont.)
B. Classification of crime scenes can be based on . . .
1.location
a.primary: site of original or first criminal activity
b.secondary: any subsequent sites of criminal activity
2.size
Note: Each
crime scene
cancomposed
be a combination
a.macroscopic
crime scene:
of many crime
scenesclassifications.
(overall area)
of these
Also as an
b.microscopic crime scene: focused on specific types
investigation
proceeds, the definition of the
of physical evidence found at the macroscopic crime
crime scene
scene can be constantly modified.
3. type of crime committed
a. homicide
b. robbery
c. sexual assault
d. etc.
4. condition of the crime
scene
a. organized
b. disorganized
6. physical location
of crime scene
a. indoors
b. outdoors
c. vehicle
d. etc.
7. others
III. General procedures for CSI
(recognition step)
A. Secure and protect the crime scene
1. First responding officer
a. critical role
b. responsibilities include:
i. assist the victim
ii. search for and arrest suspects if possible
iii. detain all witnesses
iv. protect and secure the scene
v. note and communicate to investigators
all movements and alterations made to
the scene
http://www.fundraw.com/clipart/clip-art/00000898/Police-Officer/
III. General procedures for CSI
A. Secure and protect the crime scene (cont.)
2. Establish crime scene security
a. Why? Locard’s Principle
b. Multi-level approach
http://shine4ever.files.wordpress.com/2009/08/crime-scene-tape-police-lights.jpg
James, S.H., & Nordby, J.J. (2005). Forensic Science: An Introduction to Scientific and
Investigative Techniques. 2nd Edition. New York: Taylor & Francis. Pg. 171.
III. General procedures for CSI (cont.)
B. Survey the scene
1. “Walk-through”
2. Note: transient (temporary) or conditional
(the result of an action) evidence, points of
entry and exit, and initial observations
C. Documenting a crime scene
Four main components = notes,
photography, videotape, sketch
(see concept map or web for explanations)
III. General procedures for CSI (cont.)
D. Crime Scene Searches
1. Preliminary search
a. done once the scene is secured
b. purpose = note obvious evidence
2. Post-documentation search
a. intensive search for less obvious/overlook
evidence
b. completed before collection and packaging of
evidence
c. evidence found must be documented before
collection
III. General procedures for CSI
D. Crime Scene Searches (cont.)
3. Search methods/patterns
a. Purpose = provide systematic search so no
evidence missed
b. Organized = everyone on same page and
stress no touching or altering evidence (just
mark they are there)
c. Six most common search patterns
1. Link
2. Line or Strip
3. Grid
4. Wheel or Ray
5. Spiral
6. Zone
1
2
3
4
III. General procedures for CSI (cont.)
E. Collection of Evidence
1. Done AFTER crime scene documentation and
intensive search for evidence
2. Evidence collector = one person given this job
--Why?
To ensure evidence collected, packaged, marked,
sealed, and preserved in CONSISTENT manner
3. Order of collection
a. no set order
b. depends on nature of the evidence
--example: transient, fragile, or easily lost
evidence collected first
4. IMPORTANT: if any new evidence discovered, must
first DOCUMENT it before collecting
III. General procedures for CSI
E. Collection of Evidence (cont.)
5. General collection guidelines
a. Most items packaged in primary container, then
placed inside secondary container
b. Outer container
i.
completely sealed at time of collection with
tamper-resistant tape
ii. marked with: items contained; ID of collector;
time, date, and location of collection
c. Each item packaged SEPARATELY to prevent
cross-contamination
http://www.fbi.gov/publications/leb/2006/april2006/page25.jpg
III. General procedures for CSI
E. Collection of Evidence (cont.)
6. Ways to package different categories of evidence
a. Biological material
--packaged in a dry paper bag (NOT plastic)
b. 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
c. Fingerprints
--lifted fingerprints are attached to an index card
d. Arson debris
-- packaged in old paint cans or mason jars (sealed
glass jar)
e. Castings
--packaged in a box with cushioning
http://www.shenet.org/High/hsacaddept/science/jstdenis/F
orensic%20Science/PowerPoint%20Presentation.swf
III. General procedures for CSI (cont.)
F. Crime Scene Reconstruction
1. The process of analyzing data to ultimately
develop a theory of the crime
2. Stages involved (see diagram and
explanations on page 180 of textbook):
a.
b.
c.
d.
e.
Data collection
Conjecture
Hypothesis formation
Testing
Theory formation
CS sketching is the final step in CS documentation
Provides for dimensional relationships
2 views
1. Bird’s eye view (top-down/overhead . . .most common)
2. Elevation view (side-on)
2 types
1. Rough sketch—completed at scene, not to scale
2. Final sketch—completed later with lots of time and detail,
drawn to scale
1. Triangulation (indoor)
RP
RP
RP
evidence
evidence
2. Rectangular coordinates (indoor)
3. Baseline (outdoor)
evidence
RP
RP
evidence
evidence
evidence
4. Polar coordinates (outdoor)
 Label North
 Label RP
 Use rectangular coordinates to
measure evidence
door
 Symbols
window
 Use RULER in final sketch and
tables
 Final sketch drawn to
SCALE (include key to
scale)
 Evidence table
Letter
 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
Item/description
Location
From N
From W
A
B
C
Body
 Use detail when including item
description (ie. Book . . . What
book? Size?—measure
dimensions)
= 1foot