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| A List Of Suspects |
| 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 composite
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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