How Are Fingerprints Used in Forensic Science?
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Historic Use
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Forensic science is the area of study involving crime scene investigation. Forensic scientists are trained to make a hypothesis utilizing multiple sources of evidence including fingerprints. Fingerprints were first used in criminal investigations during the mid-1850s in India, but they were not used as regular protocol in England and Wales until 1901, according to historian Simon A. Cole.
Despite the fact that a national fingerprint data base in the U.S. would offer investigators a valuable pool of information on individuals participating in criminal behavior, the push to collect fingerprints in the U.S. came only out of prejudice against foreign-born individuals during the 1940s, according to Cole's book "Suspect Identities: A History of Fingerprinting and Criminal Identification."
Modern Fingerprint Collection
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The Federal Bureau of Investigation fingerprint database today holds over 60 million sets of prints, with over 200,000 sets newly entered each day, according to Criminal Justice Information Services spokesman Stephen Fischer in an article printed in "Wired" magazine on July 23, 2009. The new sets are collected from individuals applying for licenses or security clearances and from people accused and convicted of crimes. The FBI database also contains partial fingerprints, incomplete sets, or partial images taken from crime scenes. Fischer states that between 1,000 and 2,000 partials are received daily by the FBI.
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Fingerprint Analysis
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Manually collected prints (achieved by inking fingers and transferring the image to a cardboard file) are scanned as computer files and then placed into programs that evaluate the print. Technologically advanced offices also scan prints directly into computer software. Fischer says that the FBI program compares nearly 200,000 prints per day using the 60 million sets in the database. Storing this amount of data is challenging. Christopher M. Brislawn, a digital signal processor working at the Los Alamos National Lab, explains the difficulties of scanning an accurate image on his website (listed below under Resources). Fingerprint files require image compression to save storage space, but this process degrades the print image. Brislawn was part of a team that developed a compression standard (officially titled the Wavelet-Scalar Quantization Standard) to reduce the amount of graininess in the images.
Positive Fingerprint Identification
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Fingerprint identification is done by trained specialists who examine the print for specific areas that match. Rarely do criminals leave perfect prints at a crime scene, and so various parts of the print are used, including ridges, print shapes, and even sweat pores in the fingertip. Fingerprint evidence is used to identify individuals in court trials. Presiding over a 2002 case where fingerprint evidence was pivotal in the subject identification, Pennsylvania federal court Judge Louis Pollak ruled that interpretation of fingerprint evidence is "scientifically unreliable," and determined that the process allowed too much subjectivity. He later reversed his decision, but use of print identification in court proceedings continues to be critically evaluated by many courts.
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nc info. :D
