Forensic Digital Photography Techniques
Forensic photography is used to document and support crime scene findings. Photographs of the scene --- before anything is processed or moved by investigators --- can become vital pieces of evidence. Techniques for forensic photography include alternative lighting sources, micro and macro photography, and contrast photography. Lighting techniques are the most crucial aspect of forensic photography, however multiple techniques are often used to properly document the scene.
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Basic Techniques
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Photograph the scene from all corners and angles. Include panoramic views to document the location of the evidence in relation to other markers and landmarks at the scene. Several photographs of each area and room may be necessary to document the full scene. Individual pieces of evidence should be photographed from a distance as well as close up. When needed, measuring devices can be placed next to the evidence to document size or distance from other objects.
Chemiluminescence
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Chemiluminescence is the science of using chemicals to create reactions causing matter to illuminate. Chemicals like Luminol are used to illuminate bodily fluids that are present on crime scene surfaces, including those that have already been cleaned. Once sprayed on an aspect of the crime scene, the chemical takes about five seconds to produce a blueish glow on blood evidence. This technique is used in a dark room and requires the camera equipment to be set up before spraying.
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Cyanoacrylate
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Cyanoacrylate fuming, also known as the super glue method, is the technique of using fumes to produce a chemical reaction that changes the composition of latent fingerprints. Fingerprints leave behind amino acids, fatty acids and proteins. The fuming reaction produces a sticky white residue that clings to the edges of the fingerprint ridges. This method will allow for photographing the print in it's original location.
Alternative Lighting
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Forensic photographers can use alternative lighting sources for illuminating crime scene evidence, such as ultraviolet, infrared and fluorescent lighting. These lights enhance wavelengths that are not capable of being seen with the human eye and cause the evidence to fluoresce in greater levels of detail. Alternative lighting techniques are often used in conjunction with chemiluminescence and cyanoacrylate fuming.
Photomacrography and Photomicrography
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Photomacrography and photomicrography are methods of taking close-up pictures. Macro photographs are simply magnified images, or images that you have zoomed into to obtain a better image. An example would be photographing a hair fiber on a victim's shirt. Micro photographs are images that were taken using microscoping lenses to capture elements that cannot be seen by the human eye. An example would be photographing the texture of the hair fiber found on the victim's shirt.
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