Crime Scene Investigation
At the crime scene
Crime scene investigators only have one chance to get things right!!
Successfully prosecuting suspects depends on how evidence is handled.
Cases where improper handling of crime scene evidence may have
impacted the outcome of a case:
• JonBenet Ramsey
• O.J. Simpson
At the Crime Scene
Protect:
When a crime is called in, the first officer at the scene should:
* Get medical assistance for injured people
• protect the scene to prevent the destruction of evidence
(often officers stand there for hours waiting for a search warrant)
• anyone not involved in the investigation should be kept out
• no one should use the toilet, towels, phone, lights, etc.
At the Crime Scene
Record:
When an investigator (detective) first arrives at the scene they
do the following:
• interview witnesses
• consider legal aspects (search warrants)
• take meticulous notes (it might take years to get to court)
• document the scene by photographing and making a rough sketch
At the Crime Scene
Sketch:
• A rough sketch is done
at the crime scene.
• It includes measurements,
Compass direction, and a
legend.
• A smooth sketch is
done at the lab.
• It includes a scale,
Compass direction, and a
legend.
• This is what is shown to a
jury.
At the Crime Scene
Notes:
• There cannot be enough notes taken
• Notes should be in chronological order, detailed, and thorough
• Notes are never to be discarded
At the Crime Scene
Search:
• Depending on the location of the crime scene one of four search
patterns will be used to look for evidence
Spiral
Quadrant
Lane
Grid
Dead Body at a picnic
Plane crash at a corn field
Murder inside a 5 bedroom house
Kidnapping at Walmart
At the Crime Scene
Collect:
Evidence that is easily lost or fragile is collected first.
This is how evidence is collected, such as:
Trace Evidence
Blood
Ballistics
Collecting and Packaging Evidence
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Place each item in a separate bag or container and label it, to
protect the item and avoid contamination.
Chain of custody: Written record of who has had the
evidence, on the label itself.

Fragile evidence such as fingerprints, hair and bloodstains are
collected first. Sometimes a piece of the surface or garmet
where this evidence is found is taken to the lab.

Pill bottles, manila envelopes and plastic bags are good
containers.
Special Considerations:

Wet items are dried to prevent mold

Containers are sealed tight to prevent breakage or leaks of
fluid or fumes

Biological items are dried and frozen

Firearms are fixed rigidly in a wooden container

Adhesive tape and vacuum cleaners are used last. They collect
evidence but also everything else.
At the Crime Scene
People found at the crime scene:
• Police Officer: Protect the scene.
• Medical Examiner: Declare death, I.D. the body, determine
cause, manner, and time of death.
• CSI Unit: Collect evidence, photo crime scene, produce rough
and smooth sketches.
• Detective: Interview witnesses, suspects, puts all the pieces
of the puzzle together.
SOMETHING TO REMEMBER…
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P rotect
P hotograph
Search
C ollect
Record
I dentify
P ackage
Transport