Forensic photography
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Forensic photography (sometimes referred to as forensic imaging or crime scene photography) is the art of producing an accurate reproduction of a crime scene or an accident scene for the benefit of a court. It is part of the process of evidence collecting. It provides investigators with photos of bodies, places, items involved in the crime. Pictures of accidents show broken machinery, or a car crash, and so on. Photography of this kind involves choosing correct lighting, accurate angling of lenses, and a collection of different viewpoints. Scales are often used in the picture so that dimensions of items are recorded on the image.
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[edit] Methods
Crime scene photographers capture images mainly in color, but also often in black and white. Various forces and different countries have different policies in regards to 35 mm film or digital photography. There are advantages and disadvantages to both. Conventional photography (even using disposable cameras) have a high resolution, enabling great enlargement should details in a picture need closer examination. Pictures from surveillance cameras are a growing source of evidence for courts, as are pictures taken by bystanders on mobile phones. The former are being used increasingly at accident blackspots, and bystanders may take pictures of events when no policeman or investigator is present, but yet may be critical to a case. Digital photographs usually have an automatic date and time marker on each image, so that authenticity can be verified. Conventional photographs without such marks must be authenticated by the photographer, usually in a witness statement. Pictures of the relative position of objects (as in a Palimpsest) can establish a sequence of events at a crime or accident scene.
Pictures as evidence must be:
- Fit for court
- A true record
- Untampered
[edit] Fit for court
The images must be clear and usually have scales. They serve to not only remind CSEs and investigators of the scene but also to provide a tangible image for the court to better enable them to understand what happened. The use of several views taken from different angles helps to minimise the problem of parallax.
Overall images do not have scales and serve to show the general layout (e.g. the house where the murder is thought to have occurred). Context images show evidence in context (e.g. how the knife was next to the sofa). Close up images show fine detail of an artefact (e.g. a bloody fingerprint on the knife).
Accident photographs show the overall layout at the scene taken from many different angles, with close-ups of significant damage, or trace evidence such as tire marks at a car crash scene. As with crime scene photography, it is essential that the site is pristine and untouched as far as is possible. Some essential intervention (rescuing a trapped victim, for example) must be recorded in the notes made at the time by the photographer, so that the authenticity of the photographs can be verified.
[edit] Untampered
Like all evidence a chain of custody must be maintained for crime scene photographs. Sometimes a CSI will process his/her own film or there is a specific lab for it. Regardless of how it is done any person who handles the evidence must be recorded. Accident scene pictures should also be identified and sourced, police photographs taken at the scene often being used in civil cases.
