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Fingerprint identification Fingerprint identification (sometimes referred to as dactyloscopy) is the process of comparing questioned and known friction skin ridge impressions (see Minutiae) from fingers, palms, and toes to determine if the impressions are from the same finger (or palm, toe, etc.). The flexibility of friction ridge skin means that no two finger or palm prints are ever exactly alike (never identical in every detail), even two impressions recorded immediately after each other. Fingerprint identification (also referred to as individualization) occurs when an expert (or an expert computer system operating under threshold scoring rules) determines that two friction ridge impressions originated from the same finger or palm (or toe, sole) to the exclusion of all others. Latent prints Although the word latent means hidden or invisible, in modern usage for forensic science the term latent prints means any chance or accidental impression left by friction ridge skin on a surface, regardless of whether it is visible or invisible at the time of deposition. Electronic, chemical and physical processing techniques permit visualization of invisible latent print residue whether they are from natural secretions of the eccrine glands present on friction ridge skin (which produce palmar sweat, sebum, and various kinds of lipids), or whether the impression is in a contaminate such as motor oil, blood, paint, ink, etc. Patent prints These are friction ridge impressions of unknown origin which are obvious to the human eye and are caused by a transfer of foreign material on the finger, onto a surface. Because they are already visible they need no enhancement, and are photographed instead of being lifted. Plastic prints A plastic print is a friction ridge impression from a finger or palm (or toe/foot) deposited in a material that retains the shape of the ridge detail. Commonly encountered examples are melted candle wax, putty removed from the perimeter of window panes and thick grease deposits on car parts. Such prints are already visible and need no enhancement, but investigators must not overlook the potential that invisible latent prints deposited by accomplices may also be on such surfaces. After photographically recording such prints, attempts should be made to visualize other non-plastic impressions deposited in natural finger/palm secretions (eccrine gland secretions) or contaminates. Classifying fingerprints Before computerization replaced manual filing systems in large fingerprint operations, manual fingerprint classification systems were used to categorize fingerprints based on general ridge formations (such as the presence or absence of circular patterns in various fingers), thus permitting filing and retrieval of paper records in large collections based on friction ridge patterns independent of name, birth date and other biographic data that persons may misrepresent. The most popular ten print classification systems include the Roscher system, the Vucetich system, and the Henry system. Of these systems, the Roscher system was developed in Germany and implemented in both Germany and Japan, the Vucetich system was developed in Argentina and implemented throughout South America, and the Henry system was developed in India and implemented in most English-speaking countries.Engert, Gerald J. (1964) "International Corner" Identification News Vol 14(1) In the Henry system of classification, there are three basic fingerprint patterns: Arch, Loop and Whorl.Henry, Edward R., Sir (1900) ''Classification and Uses of Finger Prints'' London: George Rutledge & Sons, Ltd. There are also more complex classification systems that further break down patterns to plain arches or tented arches. Loops may be radial or ulnar, depending on the side of the hand the tail points towards. Whorls also have sub-group classifications including plain whorls, accidental whorls, double loop whorls, and central pocket loop whorls. Image:Arch.jpg|Arch Image:Loop.jpg|Right loop Image:Whorl.jpg|Whorl Image:Tented arch.jpg|Tented arch Timeline There is no clear date at which fingerprinting was first used. However, significant modern dates documenting the use of fingerprints for positive identification are as follows: Reliability of fingerprinting as an identification method
Brandon Mayfield A case of erroneous identification: Brandon Mayfield is an Oregon lawyer who was identified as a participant in the Madrid bombing based on a fingerprint match by the FBI. The FBI Latent Print Unit ran the print collected in Madrid and reported a match against one of 20 fingerprint candidates returned in a search response from their Integrated Automated Fingerprint Identification (IAFIS) system. The FBI initially called the match "100 percent positive" and an "absolutely incontrovertible match". The Spanish National Police examiners concluded the prints did not match Mayfield and after two weeks identified another man who matched the prints. The FBI finally acknowledged they were in error and released him from custody. In January of 2006, a U. S. Justice Department report was released which faulted the FBI for sloppy work but exonerated them of more serious allegations. The report also found that the erroneous identification was due to misapplication of the identification methodology by the examiners involved and not a reflection of the reliability of fingerprint evidence. Shirley McKie A case of erroneous identification: Shirley McKie was a police detective in 1997 when she was accused of leaving her thumb print inside a house in Kilmarnock, Scotland where Marion Ross had been murdered. Although DC McKie denied having been inside the house, she was arrested in a dawn raid the following year and charged with perjury. The only evidence was the thumb print allegedly found at the murder scene. Two American experts testified on her behalf at her trial in May 1999 and she was found not guilty. The Scottish Criminal Record Office (SCRO) would not admit any error, but Scottish first minister Jack McConnell later said there had been an "honest mistake". On February 7, 2006, McKie was awarded £750,000 in compensation from the Scottish Executive and the SCRO.* Controversy continues to surround the McKie case with calls for the resignations of Scottish ministers and for either a public or a judicial inquiry into the matter.* Stephan Cowans A case of erroneous identification: Stephan Cowans was convicted of attempted murder in 1997 after he was accused of the shooting of a police officer while fleeing a robbery in Roxbury, Massachusetts. He was implicated in the crime by the testimony of two witnesses, one of which was the victim. The other evidence was a fingerprint on a glass mug that the assailant drank water from, and experts testified that the fingerprint belonged to him. He was found guilty and sent to prison with a sentence of 35 years. While in prison he earned money cleaning up biohazards to accrue enough money to have the evidence tested for DNA. The DNA did not match his, he had already served six years in prison before he was released. William West A story that some regard as apocryphal circulates about events occurring in the early 20th century when a man was spotted in the incoming prisoner line at the U.S. Penitentiary in Leavenworth, Kansas by a guard who recognized him and thought he was already in the prison population. Upon examination, the incoming prisoner claimed to be named Will West, while the existing prisoner was named William West. According to their Bertillon measurements, they were essentially indistinguishable. Only their fingerprints could readily identify them, and the Bertillon Method was discredited. There is evidence that men named Will and William West were both imprisoned in the Federal Penitentiary in Leavenworth, Kansas, between 1903 and 1909. However, the details of the case are suspicious, especially since they differ between retellings, and the story did not appear in print until 1918. Today, people familiar with the story differ on whether the story was accurate, a case of people (possibly separated twins) who bore a striking resemblance, a case of known twins, or complete fiction. The story of Will West is mentioned on page 167 of Forensic Uses of Digital Imaging by John C. Russ, with mug shots of "the two Will Wests" on page 168. It should be noted that the West case is not is a case of fingerprint error, but an error in the method of anthropometry, which the fingerprint science replaced. Footprints Friction ridge skin present on the soles of the feet and toes (plantar surfaces) is as unique as ridge detail on the fingers and palms (palmar surfaces). When recovered at crime scenes or on items of evidence, sole and toe impressions are used in the same manner as finger and palm prints to effect identifications. Footprint (toe and sole friction ridge skin) evidence has been admitted in US courts since 1934 (People v. Les, 267 Michigan 648, 255 NW 407). Footprints of infants, along with thumb or index finger prints of mothers, are still commonly recorded in hospitals to assist in verifying the identity of infants. Often, the only identifiable ridge detail in such impressions is from the large toe or adjacent to the large toe, due to the difficulty of recording such fine detail. When legible ridge detail is lacking, DNA is normally effective (except in instances of chimaerism) for indirectly identifying infants by confirming maternity and paternity of an infant's parents. It is not uncommon for military records of flight personnel to include bare foot inked impressions. Friction ridge skin protected inside flight boots tends to survive the trauma of a plane crash (and accompanying fire) better than fingers. Even though the U.S. Armed Forces DNA Identification Laboratory (AFDIL) stores refrigerated DNA samples from all current active duty and reserve personnel, almost all casualty identifications are effected using fingerprints from military ID card records (live scan fingerprints are recorded at the time such cards are issued). When friction ridge skin is not available from deceased military personnel, DNA and dental records are used to confirm identity. US fingerprint databases The FBI manages a fingerprint identification system and database called IAFIS, which currently holds the fingerprints and criminal records of over fifty-one million criminal record subjects, and over 1.5 million civil (non-criminal) fingerprint records. US Visit currently holds a repository of over 50 million persons, primarily in the form of two-finger records (by 2008, US Visit is transforming to a system recording FBI-standard tenprint records). Fingerprint compression Most American law enforcement agencies use Wavelet Scalar Quantization (WSQ), a wavelet-based system for efficient storage of compressed fingerprint images at 500 pixels per inch (ppi). WSQ was developed by the FBI, the Los Alamos National Lab, and the National Institute for Standards and Technology (NIST). For fingerprints recorded at 1000 ppi spatial resolution, law enforcement (including the FBI) uses JPEG 2000 instead of WSQ. Fingerprint locks In the 2000s, electronic fingerprint readers have been introduced for security applications such as identification of computer users (log-in authentication). However, early devices have been discovered to be vulnerable to quite simple methods of deception, such as fake fingerprints cast in gels. In 2006, fingerprint sensors gained popularity in the notebook PC market. Built-in sensors in ThinkPads, VAIO laptops, and others also double as motion detectors for document scrolling, like the scroll wheel. Fingerprints in other species The Koala is one of the few mammals (other than primates) that has fingerprints. In fact, koala fingerprints are remarkably similar to human fingerprints; even with an electron microscope, it can be quite difficult to distinguish between the two. • See also News stories | |||||||||||
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