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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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The most basic examination on any piece of evidence is underneath
the microscope. Photo courtesy of Californian
Association of Criminalists. |
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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 normal
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 normally 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. |
| *Rolled
up sleevs, pockets and other miscellaneous slots are appropraite
places to search for trace evidence. Photo courtesy of www.morguefile.com.
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