General Study Guide - Ontario Police College

Examining the Crime Scene (O.P.C. Training Manual)
(Crime Scene Walkthrough and Crime Scene Photography)
Introduction:
One of the greatest pioneers in the use of scientific evidence was Edmund Locard (1877-
1966).
“Every contact leaves a trace.” His principle also implies that at the same time the subject
will take away on his/her person, clothing, car, tools, weapons etc., traces of the scene or
the victim.
Contamination of the Scene:
Contamination of the scene by persons who have entered the area subsequent to the
offence creates a problem of determining which traces were left by the criminal and which
were left by the complainant (or investigators, 1 st responders etc.)
Record identification information of ALL individuals who may have entered the scene.
May need to obtain necessary samples from these individuals for elimination purposes.
Planning the Search:
Obtain as much information as possible about the offence and the scene itself before you
commence a search of physical evidence.
Complete information will assist you to make informed decisions on what to look for, where
to look and which methods to use in collection and preservation of evidence. It will also
lessen the chances of inadvertently overlooking or destroying evidence.
Keep in mind that some information provided may not be accurate.
Photographing the Scene:
Photographs are taken to record the conditions at the scene and the appearance and
location of individual objects of evidence.
When evidence is located overall locating views, medium range views and very close-up
views are taken.
The Search for Physical Evidence:
Search of evidence begins after taking the overall, or general, scene photographs.
Generally follow the sequence outlined below when conducting a search:
o The Route to the Scene
• This might also be referred to as ‘the path of entry’.
• You may be able to determine the culprit’s approach or path to the point of
entry.
• Look for footwear impressions, fibres and items that may have been dropped
– as quickly as possible to avoid accidental destruction or loss of evidence.