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| When police have a collection
of suspect photos and mug shots, they rely largely on
witness identification to collect evidence. In court,
witnesses may testify as a form of evidence, for they
are often confident of what the criminal's physical
appearances were. However, relying on witness accounts
of an event is not always accurate and false information
can lead to a wrong conviction. |
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Choose one of
the following topcis to learn more:
--> Line
ups
--> Other
ways of picturing
--> Limitations
--> Surveillance
cameras
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| Line
Ups |
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Line-ups involve known suspects
standing in a line while a witness walks along the
line and chooses those who they remember being responsible
for the crime, based on memory of height and appearance.
The witness is not visible to the suspects thanks
to a reflective glass, which allows the witness to
see through the glass, but only allows those on the
other side to see a mirror reflection.
Line-ups are an effective
method of identification if suspects are known, but
when they are not known, another approach involving
mug shots is taken. A witness peruses a series of
mug shots of previous offenders to try and pick out
a suspect, if one is present. The drawbacks to this
method is mainly the fact that it's more suited to
small communities, where there is a small enough number
of offenders for a witness to view every mug shot.
Also, as the witness is only viewing previously offending
criminals, an incorrect choice can lead police to
an innocent ex-offender.
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| Other
Ways of Picturing |
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| If the above approaches
are impractical or fail to reveal anything, police create
a likely picture of an offender, based on eyewitness
accounts. Using paint-by-number face composites
computer programs, sketches, and photo composites, witnesses
are able to choose appropriate facial hair, eye, skin
and hair colour and facial build to create a picture
that resembles who they witnessed. |
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| Limitations |
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| All of the methods mentioned
contain the same limitation, witness's memory. People
often over-estimate their ability to recall a person's
face and in the case of a violent or threatening attack,
witnesses are often more busy focusing on the attacker's
weapon than on there face of the attacker. In light
of this, governments have brought in new legislation
to tighten ID procedures and ensure that police concentrate
on more solid forensic evidence. |
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| Surveillance
Cameras |
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| Surveillance
cameras are one example of measures put in place to
enhance what the human memory is not able to do, but
it is not always as helpful as police would like it
to be. The images taken on surveillance cameras are
often tarnished and unclear, making the process of trying
to match faces with those on screen very difficult.
To make the matching of faces difficult to challenge
in court, a process called photoanthropometry is used.
This involves using a program that has the ability to
measure the exact distance between features on a suspect's
face on the video. This can then be used later to compare
with facial features on a mug shot. |
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Public surveillance cameras allow 24 hour coverage of
any crimes which may take place in the streets. Photo
couresty of www.imageafter.com. |
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