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Fingerprinting methods vary depending on the type of fingerprint and substance. Visible fingerprints are easy to find, while latent fingerprints require chemical application. Newer methods capture images without introducing chemicals. Fingerprinting is used to identify suspects, involving finding and documenting fingerprints through visual observation or chemical application. There are three types of fingerprints: visible, indented/molded, and latent. Latent fingerprints are made up of natural skin oils and require chemical application to become visible. Newer methods use digital imaging to avoid damaging the fingerprint.
There are several methods of fingerprinting and the method used generally depends on the type of fingerprint and the substance on which the fingerprint appears. One of the simplest types of detection is to visually find and photograph a visible fingerprint on a surface. This is impractical for latent fingerprints, however, and so a number of other means are usually employed often involving the application of some type of chemical that makes the fingerprints visible or allows them to be captured by other means. Newer fingerprinting methods are typically intended to capture an image of a fingerprint without introducing other chemicals that can potentially damage the fingerprint as evidence.
Fingerprinting is typically the process of finding and documenting fingerprints during some form of criminal investigation. It has been used for more than a century in an attempt to identify people who may have been involved in a criminal action, usually unidentified suspects. The process usually involves finding the fingerprints through a number of different methods and then photographing or capturing an image of the prints for future use.
There are generally three different types of fingerprints that can be found and documented through fingerprinting. The first two types are both visible forms of fingerprints, and finding them usually involves searching and basic visual observation. Indented or molded fingerprints are physically made of a soft or malleable substance such as wax or putty; visible fingerprints are made easy to see. This can include fingerprints which are positive images resulting from a finger that had ink or blood on it and placed it on a surface, leaving an image of the fingerprint. There are also negative images such as a dusty shelf revealing a fingerprint left in the dust removed by a finger that has touched the shelf.
The third type of fingerprints that can be found through fingerprint detection are latent fingerprints, those not immediately visible through basic visual search. These imprints are often left on surfaces and are made up of a finger’s natural skin oils that have remained on the surface. Fingerprinting these types of printouts often involves processes that allow the printouts to become visible for documentation.
This type of fingerprinting is usually achieved through the application of chemical liquids or powders, such as 1,8-Diazafloren-9-one (DFO), which make the oils or amino acids in the fingerprint visibly fluoresce or otherwise photographed. There are some problems with these methods, however, such as the dependence on the contrast between the fingerprint and the surface it’s on, and the possibility that those chemicals will destroy or corrupt the print. Newer methods include using techniques such as micro X-ray fluorescence (MXRF) to not change the fingerprint, but instead capture the image digitally. This type of system detects and photographs salts and other chemicals in human sweat to capture an image without applying chemicals.
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