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Unit 1 - The Crime Scene Cheat Sheet by

These are the main points covered under Unit 1.

Steps to Processing the Crime Scene

Pneumonic Device
1st P
Preserve Life (provide medical aid if needed)
2nd P
Protect the scene (close off the crime scene)
3rd P
Photograph the scene
Search the scene
Collect evidence
Record (write down important info)
Identify (do a quick scan of the evidence)
Package the evidence in the approp­riate container
Transfer evidence collected to the crime lab

Lawful Searches

To conduct a LEGAL search, officers must have at least 1 of the following:
Probable cause, consent, or a warrant
Probable Cause
A reason to suspect that a person has committed a crime
Permission from the person or property owner
Search Warrant
a legal document author­izing a police officer or other official to enter and search premises.

Crime Scene Searches

Do not dismiss any evidence until you figure out whether it is relevant or not
Crime scenes should be searched method­ically (with a plan, not randomly)
Which should be searched first: outdoor or indoor crime scenes?
Outdoor (weather may alter evidence and it is harder to protect)
Inward Spiral pattern
Starts at the perimeter of the scene and works toward the center. Good to use when there is only 1 CSI at the scene
Outward Spiral pattern
Start at the center, work your way out
Parallel or Line pattern
All members of the CSI team form a line and walk from one end of the crime scene to the other. Good for large open spaces like a field.
Grid search pattern
Is 2 parallel searches offset by 90°. Good if a more thorough search is needed
Zone or Quadrant
CSIs divide up into groups and each search their section. Example in a house someone would search the living room, someone else searches the bathroom & bedrooms.

Search Patterns


Crime Scene Sketches

Rough Crime Scene Sketch
Quickly done by a CSI member at the scene. The focus is on getting the layout­/lo­cat­ion­/me­asu­rements of evidence at the scene down correctly. Artistic design is not important at the moment.
Final Crime Scene Sketch
Is a refined version of the rough crime scene sketch, usually done on the computer or on nice paper. Design is more important here, as this will usually be presented in court.
Reference Points
Fixed, unmoveable points in the crime scene that help us determine the location of our evidence.

Rough vs. Finished Crime Scene Sketch



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