AskDefine | Define thumbprint

Dictionary Definition

thumbprint n : fingerprint made by the thumb (especially by the pad of the thumb)

User Contributed Dictionary



  1. A print, mark or impression made by a thumb.

Extensive Definition

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 and fingers) or plantar (sole and toes) skin, consisting of one or more connected ridge units of friction ridge skin. 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).

Fingerprints in other species

Some other animals, including gorillas, koalas, and fishers have their own unique prints. 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. Gorillas have fingerprints while chimpanzees don't, even though the latter are more closely related to humans.

Fingerprints as used for identification

Fingerprint identification (sometimes referred to as dactyloscopy) or palmprint identification is the process of comparing questioned and known friction skin ridge impressions (see Minutiae) from fingers or palms to determine if the impressions are from the same finger or palm. 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.
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.

Fingerprint capture

Livescan devices

Fingerprint image acquisition is considered the most critical step of an automated fingerprint authentication system, as it determines the final fingerprint image quality, which has drastic effects on the overall system performance. There are different types of fingerprint readers on the market, but the basic idea behind each capture approach is to measure in some way the physical difference between ridges and valleys. All the proposed methods can be grouped in two major families: solid-state fingerprint readers and optical fingerprint readers. The procedure for capturing a fingerprint using a sensor consists of rolling or touching with the finger onto a sensing area, which according to the physical principle in use (capacitive, optical, thermal, etc.) captures the difference between valleys and ridges. When a finger touches or rolls onto a surface, the elastic skin deforms. The quantity and direction of the pressure applied by the user, the skin conditions and the projection of an irregular 3D object (the finger) onto a 2D flat plane introduce distortions, noise and inconsistencies in the captured fingerprint image. These problems result in inconsistent, irreproducible and non-uniform contacts and, during each acquisition, their effects on the same fingerprint results are different and uncontrollable. The representation of the same fingerprint changes every time the finger is placed on the sensor platen, increasing the complexity of the fingerprint matching, impairing the system performance, and consequently limiting the widespread use of this biometric technology.

Print types

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 contaminant such as motor oil, blood, paint, ink, etc.
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.”

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 generally photographed instead of being lifted in the same manner as latent prints. 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 develop other non-plastic impressions deposited at 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 Classification 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..
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. In 14th century Persia government officials would use their fingerprint in much the same way we use signatures today. A list of significant modern dates documenting the use of fingerprints for positive identification are as follows:

Validity of fingerprinting as an identification method

The validity of forensic fingerprint evidence has recently been challenged by academics, judges and the media. While fingerprint identification was an improvement over earlier anthropometric systems, the subjective nature of matching, along with the relatively high error rate of matches when compared to DNA, has made this forensic practice controversial.
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.


The words "Reliability" and "Validity" have specific meanings to the scientific community. Reliability means successive tests bring the same results. Validity means that the results accurately reflect the external criteria being measured.
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)
  • Established the first professional certification program for forensic scientists, the IAI's Certified Latent Print Examiner program (in 1977), issuing certification to those meeting stringent criteria and revoking certification for serious errors such as erroneous identifications.
  • Remains the most commonly used forensic evidence worldwide—in most jurisdictions fingerprint examination cases match or outnumber all other forensic examination casework combined.
  • Continues to expand as the premier method for identifying persons, with tens of thousands of persons added to fingerprint repositories daily in America alone—far outdistancing similar databases in growth.
  • Is claimed to outperform DNA and all other human identification systems (fingerprints are said to solve ten times more unknown suspect cases than DNA in most jurisdictions).
  • Fingerprint identification was the first forensic discipline (in 1977) to formally institute a professional certification program for individual experts, including a procedure for decertifying those making errors. Other forensic disciplines later followed suit in establishing certification programs whereby certification could be revoked for error. 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 IAFIS—Integrated Automated Fingerprint Identification 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 FBI acknowledged the error, and a judge released Mayfield after two weeks in May 2004.

Shirley McKie

Error in 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 detective constable 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

Error in identification. Stephan Cowans (d. 2007-10-25) 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 whom 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 until he could afford to have the evidence tested for DNA. The DNA did not match his, but he had already served six years in prison before he was released.

Fingerprinting of children

see Biometrics in schools Various schools have implemented fingerprint locks or registered children's fingerprints. This happened in the United Kingdom (fingerprint lock in the Holland Park School in London, databases, etc.), in Belgium (école Marie-José in Liège), in France, in Italy, etc. The NGO Privacy International has alerted that tens of thousands of UK school children were being fingerprinted by schools, often without the knowledge or consent of their parents. In 2002, the supplier Micro Librarian Systems, which use a technology similar to US prisons and German military, estimated that 350 schools through-out Britain were using such systems, to replace library cards. Under the Data Protection Act (DPA), schools in the UK do not have to ask parental consent for such practices. Parents opposed to such practices may only bring individual complaints against schools..
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.

U.S. databases and compression

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. U.S. Visit currently holds a repository of over 50 million persons, primarily in the form of two-finger records (by 2008, U.S. Visit is transforming to a system recording FBI-standard tenprint records).
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.

Locks and other applications

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.
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.


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 U.S. 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.

Lifestyle information

The secretions, skin oils and dead cells in the fingerprint contain residues of various chemicals and their metabolites present in the body. These can be detected and used for forensic purposes. For example the fingerprints of tobacco smokers contain traces of cotinine, a nicotine metabolite; they also contain traces of nicotine itself; however that may be ambiguous as its presence may be caused by mere contact of the finger with a tobacco product. By treating the fingerprint with gold nanoparticles with attached cotinine antibodies, and then subsequently with fluorescent agent attached to cotinine antibody antibodies, a fingerprint of a smoker becomes fluorescent; non-smoker's fingerprint stays dark. The same approach is investigated to be used for identifying heavy coffee drinkers, cannabis smokers, and users of various other drugs.


External links

Commercial Sites & Societies
thumbprint in Arabic: بصمة الأصبع
thumbprint in Asturian: Buelga dactilar
thumbprint in Catalan: Reconeixement d'empremtes dactilars
thumbprint in Czech: Daktyloskopie
thumbprint in Danish: Fingeraftryk
thumbprint in German: Fingerabdruck
thumbprint in Spanish: Huella dactilar
thumbprint in French: Empreinte digitale
thumbprint in Galician: Pegada dactilar
thumbprint in Korean: 지문
thumbprint in Croatian: Daktiloskopija
thumbprint in Indonesian: Sidik jari
thumbprint in Italian: Impronta digitale
thumbprint in Hebrew: טביעת אצבע
thumbprint in Malayalam: വിരലടയാളം
thumbprint in Malay (macrolanguage): Cap jari
thumbprint in Dutch: Dactyloscopie
thumbprint in Japanese: 指紋
thumbprint in Norwegian: Fingeravtrykk
thumbprint in Portuguese: Impressão digital (anatomia)
thumbprint in Russian: Дактилоскопия
thumbprint in Slovak: Daktyloskopia
thumbprint in Slovenian: Prstni odtis
thumbprint in Serbian: Отисак прста
thumbprint in Serbo-Croatian: Daktiloskopija
thumbprint in Finnish: Sormenjälki
thumbprint in Swedish: Fingeravtryck
thumbprint in Turkish: Parmak izi
thumbprint in Ukrainian: Дактилоскопія
thumbprint in Chinese: 指紋

Synonyms, Antonyms and Related Words

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