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Crime Scene Investigation
Elkins
The Seven S’s of Crime Scene Investigation
1. Secure the scene
2. Separate the witnesses
3. Scan the scene
4. Seeing the scene
5. Sketch the scene
6. Search for evidence
7. Secure the collected evidence
6. Searching for Evidence
Depends on number of investigators
Walk the scene marking location of evidence, photo, sketch
Single investigator: use grid, linear or spiral
Group: linear, zone or quadrant pattern
Stick to one pattern and one supervisor
Patterns are systematic to ensure no area is left unsearched
Additional light for hair / fibers
Vacuum cleaner
Flashlight and forceps reduce picking up extraneous
Better to collect everything and not need it than fail to collect something and need it late
Grid
Linear
Quadrant/Zone
7. 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.
An evidence log and a chain of custody document must be attached to the evidence container.
The Golden Hour – the window of opportunity to collect time-sensitive information or evidence
The evidence log should contain all pertinent information, including:
Case number, item inventory number, description of the evidence, name of suspect, name of victim, date and time of recovery, signature of person recovering the evidence, signature of any witnesses present during collection.
Packaging Evidence
Liquids and arson remains = airtight, unbreakable container
Biological evidence: breathable containers to reduce
Each item must be placed in a separate container, and sealed and labeled
The most fragile evidence is collected and packaged first
Druggist fold:
Crease 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
Evidence Bag
Maintaining a chain of custody log is essential to present credible evidence in court
Chain of Custody
1. -Bag the evidence -Add identification -Seal it -Sign it across the sealed edge
2. -Sign over to a lab technician -Open bag on non-sealed edge
3. -Return items to the evidence bag -Seal evidence bag in another bag -Sign the evidence log
Forensic Science: Fundamentals
& Investigations, Chapter 2
What determines the type and manner of
collecting and preserving physical evidence?
The nature of the evidence
Q. What type of evidence is to be retrieved
from a deceased victim for examination in
the crime laboratory?
Clothing
Fingernail scrapings
Head and pubic hairs
“Orifice” swabs
Bullets
Hand swabs for gunshot residues
Analyze the Evidence
Facts result from collected evidence processed by the
forensic lab
Lead detectives aim to see how facts fit into the crime
scenario
Lab results can:
Show reliability of witness accounts
Establish the identity of suspects or victims
Show suspects to be innocent or link them with a scene
or victim
Forensic Files
https://www.youtube.com/wat
ch?v=-r4irK1k0Fc
https://www.youtube.com/wat
ch?v=mxvyZHX1bQ4
How was the crime scene protected?
What types of forensic evidence
were discovered at the scene?
What types of evidence were
discovered in the property of the
suspect?
What methods of science were used
to tie the evidence to the crime
scene?
What evidence was used to convict
the suspect?