The Crime Scene
Processing a Crime Scene
Objectives Do Now Homework
Students will be able to: Ask students who is at the
1.List and describe the steps crime scene first and what
to take when processing a do they do.
“Oh, how simple it would all have been had I been here before they came like a herd of
buffalo and wallowed all over it.” A. Conan Doyle, the Boscombe Valley Mystery, 1892
1. What is the definition of a crime scene?
A crime scene is any place where evidence may be located to help explain events.
This evidence must be carefully, systematically, scientifically, and legally collected.
The evidence gathered must be used to
a. reconstruct a sequence of events
b. the modus operandi,( the characteristic method of operation of a criminal-
sometimes referred to as the MO)
c. and the motives of the crime.
2. The investigator must follow special steps in handling a crime scene:
A. First Responders: Preserving and isolating the crime scene
a. The first officer on the scene determines the nature of the crime
b. Provide emergency first aid for those injured at the scene
c. Arrest, detain and remove any suspect present
d. Detain witnesses, keep them separate until their statements have been
e. Ensure that the scene is safe for investigators and forensic examiners
f. Seal off the crime scene and protect any evidence it may contain
g. Maintain a single entry and exit point for all personnel
h. All visitors to the scene should wear protective coverall to avoid
contaminating the scene
i. Document all who visit the crime scene
B. Examination of the Crime Scene (senior crime scene manager)
a. Preserve and record evidence that might otherwise be destroyed.
b. Interview the first officer on the scene
c. Walk through the crime scene with first responder
d. Collect information about transient evidence (dissipated odors)
e. Manage different crime scene units
Ask students: You need to make a call to the precinct-which phone would you use?
Ask students: You need to go to the bathroom-what would you do?
Summary: Foresight and a methodical approach by those first on the scene can help
preserve and record evidence that might otherwise be destroyed. Unthinking routines,
using anything at the crime scene can destroy or dispose of vital evidence and recording
whether a door was open or closed can be the difference between a killer going free or
C. Crime Scene Photographers
a. Document key elements of the undisturbed crime scene in relation to its
b. Photographs entry and exit routes
c. Exterior shots of building
d. Connection between rooms
e. Location of evidence
f. Each photo becomes an item of evidence in itself and must include day,
date, equip used, how it was processed and a scale included with pieces of
g. Digital cameras cannot be used since images can be altered. Not admissible
unless a digital watermark can be included.
h. Use of different filters allow for the photography of certain evidence: UV
makes some stains and fingerprints glow, violet makes gunshot residues
and blood more visible, blue and green show up fibers, urine and semen.