Television shows like "CSI" and its many permutations have made the tools of forensic science as popular as the stars who use them in each episode. Chemistry, biology, psychology and physics all come into play during a forensic investigation, and you need to be able to use all sorts of tools to solve crimes. As forensic investigation has grown as a recognized field, certain tools have become standardized and extremely reliable.
DNA analysis is a reliable method for forensic investigation, and there are a variety of lab tools that can be used to do DNA testing. Samples from the crime scene such as hair, blood and other body tissues can be analyzed and used to construct a DNA type. This type can be tested against types constructed by taking samples from different suspects. The accuracy of such a match varies depending on the depth of your analysis, but if the samples match, there is little question of guilt or innocence.
Fingerprints are accepted by courts and forensic investigators as a very accurate method of identification. Latent fingerprints that have gone undetected can be preserved for a long time, sometimes even for years, at the scene of a crime. Forensic investigators use an array of chemicals and techniques to reveal fingerprints at crime scenes. Crime labs have machines that can aid in fingerprint ID, such as x-rays, vacuum coating and lighting techniques.
Image enhancement is a way of altering images from a crime scene so that important details become more evident to investigators. This technique can be used on photographs taken of evidence, security camera recordings or even impressions, such as footprints in mud. Images can be improved and manipulated digitally to reveal what was previously hidden. Lighting adjustments, such as the use of infrared light, or manipulation of image contrast can help to show details in photographs.
Ballistics is essentially a branch of physics that studies motion, trajectories and impacts. In forensic investigations, ballistics is mostly used when guns are involved in crimes. One of the key applications of ballistics is in the analysis of gunshots and matching bullets to specific guns. A gun's firing pin and the "rifling," or grooves inside the barrel, make unique signatures on bullet casings and slugs. If a suspect is found with a gun, it can be connected to a slug or casing found at the crime scene.
Chromatography is used to separate different chemical components by exaggerating the differences between them. This allows investigators to identify the different substances present in one area, such as distinguishing between different types of shattered glass or isolating fibers from clothing on a carpet. Chromatography makes the distinctions that even the most powerful microscope can't make, allowing investigators to focus individually on substances present at the scene.
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