CRIME SCENE INVESTIGATION &
EVIDENCE COLLECTION
CSI team and Crime lab
The Seven S’s of Cime Scene
Investigation
Responsibilities of first officer
1. Obtain medical assistance for anyone in need
2. Arrest any perpetrators
3. Exclude all unauthorized personnel
4. Isolate the area
5. Determine the boundaries of crime scene
6. Entry and exit points of perpetrator
7. Initial walk through
8. Develop strategy for examining and documenting crime scene
9. Determining primary and possible secondary crime scenes
10. Document and photograph obvious evidence
Crime Scene Search Patterns
photographs
• Objects must NOT be removed until photographed from all
angles
• If anything removed it should be noted and NOT be
reintroduced
• Include photos of adjacent areas, close-ups of victim’s relative
position in the scene and injuries
• If size is significant, a point of reference should be included in
the photo
• Videotaping and narrating the crime scene can also be done
Scaled sketch of the crime scene
http://vimeo.com/45223797
The Frye Standard
Frye v. United States (1923) (polygraph test
questioned)
The Frye Standard
Practical application:
Evidence
Direct Evidence
Evidence
Circumstantial (Indirect)
Evidence
Locard’s Exchange Principle
• Established by Dr. Edmond
Locard
Physical evidence
Biological evidence
• Control Sample:
• Standard/reference sample:
• Substrate control:
Packaging evidence
1.
2.
3.
4.
Create a clean paper and place
evidence in the X position
Fold in the left and right sides,
and then fold in the top and
bottom
Put the bindle into a plastic or
paper evidence bag affixing a seal
over the opening
Write your name on the seal
Chain of Custody
– Provides documentation of every person who has
come into contact with the evidence
– A paper trail
– Demonstrates to the courts that the evidence that
is being presented at trial is free of contamination,
alteration, or substitution
Bagging the evidence
1.
2.
3.
Bag the evidence
Add identification
Seal it
Sign it across the sealed edge
Sign over to a lab technician
Open bag on non-sealed edge
Return items to the evidence bag
Seal evidence bag in another bag
Sign the evidence log
• Never package wet evidence while
wet
• Blood stained material should NOT
be stored in airtight containers due
to mold potential. Paper bags or
wrapping paper used.
• Air dry clothes and place in
individual separate bags
• Charred debris from fire is sealed in
airtight containers
• Facts result from collected evidence processed by the forensic
lab
• Lead detective aims to see how facts fit into the crime
scenario
• Lab results can show the reliability of witness accounts,
establish identity of victim or suspects, show suspects
innocence or link them with the crime.
Crime scene reconstruction
Crime scene reconstruction involves:
Staging
When lab results don’t match up with the testimony of
witnesses
Common examples: