Fingerprint

This article is about human fingerprints. See also Fingerprint (disambiguation).

A fingerprint is an imprint made by the pattern of ridges on the pad of a human finger. These ridges are known as dermal ridges. Dermal ridges are not unique to humans, however, and some species of primate are also capable of generating fingerprints. Dermal ridges are commonly believed to provide traction for grasping objects. Fingerprints are usually considered to be unique, with no two fingers having the exact same friction ridge characteristics. A person's fingerprint can be used as a biometric method to identify human individuals.

The tip of a finger showing the fingerprint.

The same fingerprint as it would be detected on a surface.

Dactyloscopy

Dactyloscopy is the technique of comparing fingerprints, typically those found at the setting of a crime and those of a suspect. Due to the uniqueness of the fingers' and hands' papillar lines, it is generally considered a reliable method of identifying a person. Croat-Argentine Juan Vucetich perfected dactyloscopy in late 19th and early 20th century.

Methodology

When a person touches something with his fingers, there will usually be a visible or invisible residue left on the touched surface. The residue is patterned as a copy of the person's fingerprint and can be collected for visual study and comparison. Traditionally, finely ground powders of chalk or coal have been used to make the fingerprint clearly visible. The powder adheres to the fingerprint residue but not the surrounding surface. Sometimes the prints are invisible, in which case they are called "latent fingerprints". There are chemical techniques such as cyanoacrylate fuming and ninhydrin spray that can help make them visible.

Classifying fingerprints

There are three basic fingerprint patterns: Arch, Loop and Whorl. There are more complex classification systems that further break down the pattern to plain arches or tented arches. Loops may be radial or ulnar. Whorls also have smaller classifications. However, the five most commonly used are: whorl, radial loop, ulnar loop, arch and tented arch.

• 
  Arch
• 
  Right loop
• Whorl
  Whorl
• 
  Tented arch

Timeline

There is no clear date at which fingerprinting was first used, some examples being from prehistory. However, some significant modern dates are as follows.

• 1880: The Scot Dr Henry Faulds published his first paper on the subject in the scientific journal Nature in 1880. Returning to the UK in 1886, he offered the concept to the Metropolitan Police in London but was dismissed.
• 1892: Sir Francis Galton published a detailed statistical model of fingerprint analysis and identification and encouraged its use in forensic science in his book Finger Prints.
• 1892: Juan Vucetich, an Argentine police officer who had been studying Galton pattern types for a year, made the first criminal fingerprint identification. He successfully proved guilty Francisca Rojas, who had murdered her two sons, finding her bloody fingerprint in the crime scene.
• 1901: Sir Edward Henry devised the Henry Classification System used in England and Wales. The first fingerprinting bureau was founded in Scotland Yard
• 1902: Dr. Henry P. DeForrest used fingerprinting in the New York Civil Service.

Reliability of fingerprinting as an identification method

Fingerprints collected at a crime scene can be used in forensic science to identify suspects. Fingerprint analysis emerged in the late 19th century, when it was the first method in forensic science for unique identification. As a result of its early success, it acquired a mystique of infallibility. It has only recently been subjected to systematic analysis by investigators from outside the field. While there is some controversy over the uniqueness of fingerprints, even those who accept their uniqueness point out that it is the quality of the latent partial prints, that are usually in evidence, that is the limiting factor. As the number of defining points of these latent prints become smaller, the degree of certainty of identity declines. This is not usually quantified as a probability, as is the norm for DNA matches; "experts" commonly assert 100% certainty even though this is not statistically accurate.

Brandon Mayfield

A case of misidentifying a print: Brandon Mayfield was 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 with their Integrated Automated Fingerprint Identification (IAFIS) system. The FBI called the match "100 percent positive" and an "absolutely incontrovertible match". The Spanish National Police examiners concluded the prints did not match Mayfield and they eventually identified another man who matched the prints. The FBI later acknowledged they were in error and he was released 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.

Shirley McKie

A case of misidentifying a print: Shirley McKie was a policewoman in 1997 when she was accused of leaving her thumb print inside a house in Kilmarnock, Scotland where Marion Ross had been murdered. Although PC 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) never admitted a mistake.

On February 7, 2006, McKie was awarded £750,000 in compensation from the Scottish Executive and the SCRO.[1]

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.[2]

Stephan Cowans

A case of misidentifying a print: 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 coffee cup, 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.

Rene Ramon Sanchez

A case of mixing up prints during processing: Rene Ramon Sanchez was arrested and fingerprinted for a minor offense. His fingerprints were placed by mistake on the card prepared to hold the fingerprints of Leo Rosario, another criminal being processed at the facility at the same time. The next time Sanchez was arrested for a minor crime, he was identified as Leo Rosario, the drug dealer. Sanchez was arrested and deportation proceedings were begun. Sanchez protested but the identification by fingerprinting was considered absolute, even though no other biometric data matched

New York State Police Troop C

A case of planting print evidence: In April of 1993, Craig D. Harvey a New York State Police trooper was charged with fabricating evidence. Harvey admitted he and another trooper lifted fingerprints from items the suspect, John Spencer, touched while in Troop C headquarters during booking. He attached the fingerprints to evidence cards and later claimed that he had pulled the fingerprints from the scene of the murder. The forged evidence was used during trial and John Spencer was sentenced to 50 years to life in prison. The scandal became known when fellow trooper, David L. Harding, was interviewed for a job at the CIA. He was asked if he was willing to break the law for his country. He answered "yes", then explained how he worked to convict guilty people by fabricating evidence. He assumed the CIA would be pleased with his answer.

William West

A story that some regard as apocryphal circulates about events occurring in the late 19th 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 test of people (possibly separated twins) who bore a striking resemblance, a test of known twins, or complete fiction.

Footprints

Footprints are used to identify infants at hospitals, though this practice is not as common as it used to be, especially with DNA identification becoming more commonplace.

FBI

The American Federal Bureau of Investigation uses Wavelet Scalar Quantization (WSQ), a wavelet-based system for efficient storage of fingerprint data. WSQ was developed by the FBI, the Los Alamos National Lab, and the National Institute for Standards and Technology (NIST). The FBI manages a fingerprint identification system and database called IAFIS, which currently holds the fingerprints and criminal records of over forty-nine million subjects.

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.

See also

• New York State Police Troop C scandal
• Forged evidence

References

• New York Times; "Can Prints Lie? Yes, Man Finds To His Dismay. In front of the immigration judge, the tall, muscular man began to weep. No, he had patiently tried to explain, he was not Leo Rosario, a drug dealer and a prime candidate for deportation. He was telling the truth. He was Rene Ramon Sanchez, an auto-body worker and merengue ..."
• New York Times; July 30, 1993; "Police Investigation Supervisor Admits Faking Fingerprints"

External links

• Biometrics Research Lab
• The Fingerprints Society - Society for Fingerprint Examiners.
• Galton's Finger Prints
• Henry, Faulds, and Herschel's works on fingerprints
• Michele Triplett's Fingerprint Dictionary - Definitions, references, and more.
• Fingerprints.tk - Comprehensive site about fingerprints.
• How to fake fingerprints
• Do fingerprints lie? - The New Yorker
• Biometrics
• Will West as fable
• New York Times: Police Investigation Supervisor Admits Faking Fingerprints
• Fingerprint research and evaluation at the US National Institute of Standards and Technology