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| Every
Criminal Leaves A Trace |
| The motto 'every contact
leaves a trace' by Edmond Locard, a well known criminologist, still
guides today's investigation in that a criminal cannot prevent leaving
traces of themselves at a crime scene and always take with them some
evidence that they were present at the crime scene. It is this theory
that has helped to solve many crimes. |
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Select one of the following topics to read more:
--> Trace
evidence
--> Collection
--> Where
to search
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| Trace
Evidence |
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| Finding the
traces of evidence that could link a suspect to a crime scene is difficult,
as these are usually very vague and is easily destroyed or lost.The
term trace evidence is used to describe these small samples and covers
such artifacts as hair, paint flecks, soil, fibres, dust and tiny
pieces of glass, which can all be used to track down a criminal.
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| Collection |
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| The collection of the trace evidence
requires just as much technique, time and patience as finding ennormal
evidence. Larger pieces of trace evidence can be retrieved using a
magnifying lens and a pair of tweezers. Forensic vacuums, involving
a piece of filter paper over the suction, suck small material onto
the paper for analysis in the laboratory. Tape lifts are also effective
for removing evidence from smaller areas and investigators remove
portable objects using bags so that the smaller particles can be removed
later on in the lab. Washing and scraping these portable objects in
the lab reveals trace particles that would have otherwise escaped
unnoticed. |
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| Where
To Search |
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| Clothes that a criminal wore at the
crime scene collect dirt and other artifacts, which fall off in a
matter of hours and brushing can remove what hasn't already fallen
off, thus making such evidence relatively useless. There is however,
the exception that the clothing contains pouch like spots, which would
likely hold trace evidence. The evidence is usually so small it is
not ennormally visible to the naked eye, so investigators are faced
with the problem of needing to find something they can't see. This
problem is overcome by performing a thorough search of the crime scene
and making guesses from the search as to what they should look for
and where they might find this. For example, on a couch, seams on
the cushions, underneath the cushion and on the arms of the chair
can often contain fibres from the suspect or victim that can incriminate
a person, when at a first glance, the object appears to contain no
evidence. |
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