As an identification device, fingerprinting dates from antiquity, but modern systems began essentially with the work of Henry Faulds, William James Herschel, and Sir Francis Galton in the late 19th cent. Fingerprints gained acceptance as a more objective form of identification than visual recognition. The Galton method, elaborated by E. R. Henry, is still used in Great Britain and the United States. Juan Vucetich in Argentina, also using Galton as a guide, developed (1904) an alternate system that gained wide acceptance in Spanish-speaking countries.
Fingerprinting for identification of criminals was first used in connection with the Bertillon system. Most countries now require that all criminals be fingerprinted. Methods have also been devised for developing fingerprint impressions left by criminals at the scene of a crime. The most common uses a brush and powder to mark the fingerprint, which is then photographed and lifted from the surface using tape. The reliability of fingerprints for criminal identification is complicated by the need to use crime scene prints that may be partial or distorted and by the technical competency of the person identifying the print (computer identification is often used as an aid).
In 2002 a federal judge ruled that, because of inconsistencies in laboratory identification of fingerprints, fingerprint identification as practiced was not accurate enough to be used without qualification, and that an expert cannot testify that a person's fingerprints absolutely match those found at a crime, though an expert may point out similarity between two sets of prints and may state that no two people have identical prints. The judge reversed himself two months later, deciding that although the FBI's fingerprint identification procedures were not proven scientifically according to a strict standard they were nonetheless sufficiently reliable.
In the United States, prints also are taken of civilian government employees and members of the armed forces and by some banks and other agencies. Some states now require a thumbprint when applying for a driver's license, and banks and check-cashing institutions are increasingly requiring a thumbprint before cashing checks, particularly in states that use license thumbprints. Some stores also require thumbprints when paying by check or even by credit card. A national fingerprint file and database is maintained by the Federal Bureau of Investigation.
See C. Beavan, Fingerprints (2001), and S. A. Cole, Suspect Identities (2001). Technical works on the subject include H. C. Lee and R. E. Gaensslen, ed., Advances in Fingerprint Technology (2d ed., 2001), D. R. Ashbaugh, Quantitative-Qualitative Friction Ridge Analysis (1999), and D. L. Faigman et al., Modern Scientific Evidence (2d ed., 2002).
A fingerprint is an impression of the friction ridges of all or any part of the finger. A friction ridge is a raised portion of the epidermis on the palmar (palm) or digits (fingers and toes) or plantar (sole) skin, consisting of one or more connected ridge units of friction ridge skin. These ridges are sometimes known as "dermal ridges" or "dermal Papillae".
Fingerprints may be deposited in natural secretions from the eccrine glands present in friction ridge skin (secretions consisting primarily of water) or they may be made by ink or other contaminants transferred from the peaks of friction skin ridges to a relatively smooth surface such as a fingerprint card. The term fingerprint normally refers to impressions transferred from the pad on the last joint of fingers and thumbs, though fingerprint cards also typically record portions of lower joint areas of the fingers (which are also used to make identifications).
A known print is the intentional recording of the friction ridges, usually with black printer's ink rolled across a contrasting white background, typically a white card. Friction ridges can also be recorded digitally using a technique called Live-Scan. A latent print is the chance reproduction of the friction ridges deposited on the surface of an item. Latent prints are often fragmentary and may require chemical methods, powder, or alternative light sources in order to be visualized.
When friction ridges come in contact with a surface that is receptive to a print, material on the ridges, such as perspiration, oil, grease, ink, etc. can be transferred to the item. The factors which affect friction ridge impressions are numerous, thereby requiring examiners to undergo extensive and objective study in order to be trained to competency. Pliability of the skin, deposition pressure, slippage, the matrix, the surface, and the development medium are just some of the various factors which can cause a latent print to appear differently from the known recording of the same friction ridges. Indeed, the conditions of friction ridge deposition are unique and never duplicated. This is another reason why extensive and objective study is necessary for examiners to achieve competency.
Latent prints may exhibit only a small portion of the surface of the finger and may be smudged, distorted, or both, depending on how they were deposited. For these reasons, latent prints are an “inevitable source of error in making comparisons,” as they generally “contain less clarity, less content, and less undistorted information than a fingerprint taken under controlled conditions, and much, much less detail compared to the actual patterns of ridges and grooves of a finger.”
In the Henry system of classification, there are three basic fingerprint patterns: Arch, Loop and Whorl. 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.
Fingerprints were also used as substitutes for signatures. In Babylon from 1885-1913 B.C.E., in order to protect against forgery, parties to a legal contract impressed their fingerprints into the clay tablet on which the contract had been written. By 246 B.C.E., Chinese officials impressed their fingerprints in clay seals, which were used to seal documents. With the advent of silk and paper in China, parties to a legal contract impressed their handprints on the document. Sometime before 851 C.E., an Arab merchant in China, Abu Zayd Hasan, witnessed Chinese merchants using fingerprints to authenticate loans. By 702 C.E., Japan had adopted the Chinese practice of sealing contracts with fingerprints. Supposedly, in 14th century Persia, government documents were authenticated with thumbprints.
Although the ancient peoples probably did not realize that fingerprints could identify individuals, references from the age of the Babylonian king Hammurabi (1792-1750 B.C.E.) indicate that law officials fingerprinted people who had been arrested. In China around 300 C.E. handprints were used as evidence in a trial for theft. In 650 C.E., the Chinese historian Kia Kung-Yen remarked that fingerprints could be used as a means of authentication. In his Jami al-Tawarikh [Universal History], Persian official and physician Rashid-al-Din Hamadani (a.k.a. "Rashideddin") (1247-1318) comments on the Chinese practice of identifying people via their fingerprints: "Experience shows that no two individuals have fingers exactly alike.
A list of significant modern dates documenting the use of fingerprints for positive identification are as follows:
Certain specific criticisms are now being accepted by some leaders of the forensic fingerprint community, providing an incentive to improve training and procedures. Glenn Langenburg who is a Forensic Scientist, Latent Print Examiner for the Minnesota Bureau of Criminal Apprehension, is such an individual, having written an article that responds to the most active academic critics.
Although experts are often more comfortable relying on their instincts, this reliance does not always translate into superior predictive ability.
For example, in the popular Analysis, Comparison, Evaluation, and Verification (ACE-V) paradigm for fingerprint identification, the verification stage, in which a second examiner confirms the assessment of the original examiner, may increase the consistency of the assessments. But while the verification stage has implications for the reliability of latent print comparisons, it does not assure their validity.(pp 12)
The few tests of validity of forensic fingerprinting have not been supportive of the method:
Despite the absence of objective standards, scientific validation, and adequate statistical studies, a natural question to ask is how well fingerprint examiners actually perform. Proficiency tests do not validate a procedure per se, but they can provide some insight into error rates. In 1995, the Collaborative Testing Service (CTS) administered a proficiency test that, for the first time, was “designed, assembled, and reviewed” by the International Association for Identification (IAI).The results were disappointing. Four suspect cards with prints of all ten fingers were provided together with seven latents. Of 156 people taking the test, only 68 (44%) correctly classified all seven latents. Overall, the tests contained a total of 48 incorrect identifications. David Grieve, the editor of the Journal of Forensic Identification, describes the reaction of the forensic community to the results of the CTS test as ranging from “shock to disbelief,” and added:Errors of this magnitude within a discipline singularly admired and respected for its touted absolute certainty as an identification process have produced chilling and mind- numbing realities. Thirty-four participants, an incredible 22% of those involved, substituted presumed but false certainty for truth. By any measure, this represents a profile of practice that is unacceptable and thus demands positive action by the entire community.
What is striking about these comments is that they do not come from a critic of the fingerprint community, but from the editor of one of its premier publications.(pp25)
The science of fingerprint identification can assert its standing amongst forensic sciences for many reasons, including the following:
Fingerprint identification effects far more positive identifications of persons worldwide daily than any other human identification procedure. Some of the discontent over fingerprint evidence may be due to the desire to push the conclusiveness of fingerprint examinations to the same level of certitude as that of DNA analysis. DNA is probability-based inasmuch as an individual is genetically half from the mother's contribution and half from the father's contribution. These genetic contributions are passed down from generation to generation. While pattern type (arch, loops, and whorls) may be inherited, the details of the friction ridges are not. For example, it cannot be concluded that a person inherited a certain bifurcation from their mother and an ending ridge from their father as the development of these features are completely random. Further, fingerprints as an analogy of uniqueness has been widely scientifically accepted. For example, chemists often use the term "fingerprint region" to describe an area of a chemical that can be used to identify it.
Another criticism sometimes leveled at fingerprint practice is that it is a "closed discipline". However, practitioners in the scientific community are generally specialized and may not extend to other areas of science; in this respect, fingerprint scientists are no different from the rest of the scientific community. The fingerprint community asserts that it maintains the need for objectivity and continued research in the area of friction ridge analysis.
Developing agents depend on the presence of organic deposits for their effectiveness. However, fingerprints are typically formed by the secretions of the eccrine glands of the fingertips, which principally comprise water and inorganic salts, with only a small proportion of organic material such as urea and amino acids and detecting such fingerprints is far from easy. A further complication is the fact that the organic component of any deposited material is readily destroyed by heat, such as occurs when a gun is fired or a bomb is detonated, when the temperature may reach as high as 500°C. In contrast, the non-volatile, inorganic component of eccrine secretion remains intact even when exposed to temperatures as high as 600°C.
Within the Materials Research Centre, University of Swansea, UK , University of Swansea, UK, Professor Neil McMurray and Dr Geraint Williams have developed a technique that enables fingerprints to be visualised on metallic and electrically conductive surfaces without the need to develop the prints first. The technique involves the use of an instrument called a scanning Kelvin probe (SKP), which measures the voltage, or electrical potential, at pre-set intervals over the surface of an object on which a fingerprint may have been deposited. These measurements can then be mapped to produce an image of the fingerprint. A higher resolution image can be obtained by increasing the number of points sampled, but at the expense of the time taken for the process. A sampling frequency of 20 points per mm is high enough to visualise a fingerprint in sufficient detail for identification purposes and produces a voltage map in 2–3 hours. So far the technique has been shown to work effectively on a wide range of forensically important metal surfaces including iron, steel and aluminium. While initial experiments were performed on planar, i.e. flat, surfaces, the technique has been further developed to cope with severely non-planar surfaces, such as the warped cylindrical surface of fired cartridge cases. The very latest research from the department has found that physically removing a fingerprint from a metal surface, e.g. by rubbing with a tissue, does not necessarily result in the loss of all fingerprint information. The reason for this is that the differences in potential that are the basis of the visualisation are caused by the interaction of inorganic salts in the fingerprint deposit and the metal surface and begin to occur as soon as the finger comes into contact with the metal, resulting in the formation of metal–ion complexes that cannot easily be removed.
Currently, in crime scene investigations, a decision has to be made at an early stage whether to attempt to retrieve fingerprints through the use of developers or whether to swab surfaces in an attempt to salvage material for DNA fingerprinting. The two processes are mutually incompatible, as fingerprint developers destroy material that could potentially be used for DNA analysis, and swabbing is likely to make fingerprint identification impossible.
The application of the new SKP fingerprinting technique, which is non-contact and does not require the use of developers, has the potential to allow fingerprints to be retrieved while still leaving intact any material that could subsequently be subjected to DNA analysis. The University of Swansea group hope to have a forensically usable prototype in the near future and it is intended that eventually the instrument will be manufactured in sufficiently large numbers that it will be widely used by forensic teams on the frontline.
There has recently been significant worldwide interest in the technique with articles appearing in/on BBC.co.uk , Sky News , S4C news, The Daily Mail, FHM magazine, AOL, Yahoo news, Telegraph.co.uk, The Hindu, Taipei times, Sydney Morning Herald, San Francisco Gate, The Mercury (South Africa), Brisbane Courier Mail and many others. There has also been significant interest from the Home Office and a number of different police forces across the UK.
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 retells, 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 a case of fingerprint error, but an error in the method of anthropometry, which the fingerprint science replaced.
On 29 November 2006, the FBI agreed to pay Brandon Mayfield the sum of US$2 million. The judicial settlement allows Mayfield to continue a suit regarding certain other government practices surrounding his arrest and detention. The formal apology stated that the FBI, which erroneously linked him to the 2004 Madrid bombing through a fingerprinting mistake, had taken steps to "ensure that what happened to Mr. Mayfield and the Mayfield family does not happen again."
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.
The purpose of taking children's fingerprints is to struggle against school skipping or/and to replace library cards or money for meals by fingerprint locks. In Belgium, this practice gave rise to a question in Parliament on February 6, 2007 by Michel de La Motte (Humanist Democratic Centre) to the Education Minister Marie Arena, who replied that they were legal insofar as the school did not use them for external purposes nor to survey the private life of children. Such practices have also been used in France (Angers, Carqueiranne college in the Var — the latter won the Big Brother Award of 2005, etc.) although the CNIL, official organisation in charge of protection of privacy, has declared them "disproportionate.
In March 2007, the British government was considering fingerprinting of children aged 11 to 15 as part of new passport and ID card (the latter having been recently implemented in the UK), also lifting opposition for privacy concerns. All fingerprints taken would be cross-checked against prints from 900,000 unsolved crimes. Shadow Home secretary David Davis called the plan "sinister."
Recently, serious concerns about the security implications of using conventional biometric templates in schools have been raised by a number of leading IT security experts, including Kim Cameron, architect of identity and access in the connected systems division at Microsoft, who cites research by Cavoukian and Stoianov to back up his assertion that "it is absolutely premature to begin using 'conventional biometrics' in schools".
Biometric vendors claim benefits to schools such as improved reading skills, decreased wait times in lunch lines and increased revenues. They do not cite independent research to support this. Educationalist Dr Sandra Leaton Gray of Homerton College, Cambridge stated in early 2007 that "I have not been able to find a single piece of published research which suggests that the use of biometrics in schools promotes healthy eating or improves reading skills amongst children... There is absolutely no evidence for such claims".
The Ottawa Police in Canada advised parents who fear that their children may be kidnapped to have their fingerprints taken.
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.
Another recent use of fingerprints in a day-to-day setting has been the increasing reliance on biometrics in schools where fingerprints and, to a lesser extent, iris scans are used to validate electronic registration, cashless catering, and library access. This practice is particularly widespread in the UK, where more than 3500 schools currently use such technology, though it is also starting to be adopted in some states in the US.
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.
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