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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 EvidenceDepends 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
Spiral
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.
Chain of Custody1. -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 logForensic 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
Reconstructing a Crime Scene
Crime scene reconstruction involves:
Forming a hypothesis of the sequence of events
From before the crime was committed through its commission
But wait…things just aren’t adding up between the evidence and the witnesses/suspect. Could this be staged?!
Staged Crime Scenes
When lab results don’t match up with the testimony of witnesses
Common examples:
Staging a fire—to cover bankruptcy Staging a suicide—to cover a murder Staging a burglary—to collect insurance money
Things to consider when determining staging occurred
Initially treat all death investigations as homicide
Do the type(s) of wounds found on the victim match the weapon employed?
Could the wounds be easily self inflicted?
Establish a profile of the victim through interviews with friends and family
Evaluate the behavior ( mood and actions) of the victim before the event
Evaluate the behavior ( mood and actions) of any suspects before the event
Corroborate statements with evidential facts
Reconstruct the eventConduct all forensic
examinations to determine the facts of the case