Fingerprints are the oldest and most accurate method of identifying individuals. No two people — not even identical twins — have the same fingerprints. It is extremely easy for even the most accomplished criminals to leave incriminating fingerprints at the scene of a crime.
This article provides an outline of fingerprint identification in the context of criminal evidence.
Types of Fingerprints
Each set of fingerprints has unique ridge patterns and points that trained fingerprint experts can see and identify. If experts compare two fingerprints, and one has a point not seen on the other, fingerprint examiners will deem that uniqueness as a failed match.
The fingerprints are identical if there are only matching points and no differences. There is no requirement for a set number of matching points, but the more points, the stronger the print identification.
Fingerprints fall into three groups:
Plastic fingerprints are visible to the naked eye and leave behind a three-dimensional imprint. Pressing your fingers or hand into something moldable such as wax, soap, or tar is the most common way you'll leave behind plastic fingerprints.
A patent print is the most visible fingerprint impression. A patent print is typically left behind in liquid such as blood, grease, or ink and can be seen easily with the human eye. For example, police officers may observe a bloody palm print at a crime scene.
Latent fingerprints come from sweat and oil and need additional processing to be visible. You leave latent prints on virtually every surface you touch, such as:
- Phone screens
- TV remotes
- Door handles
You can see these prints with alternative light sources, such as special ultraviolet lights. In criminal investigations, experts use fingerprint powder or chemicals to set a print. They then "lift" the print using special adhesives to complete the criminal identification.
The History of Fingerprint Identification
The use of fingerprint ID goes back to ancient times, although the use of DNA evidence is more accurate today.
In ancient Babylonia and China, thumbprints and fingerprints were used on clay tablets and seals as signatures. Some scholars trace the idea that fingerprints might be unique to individuals back to the 14th century or even earlier.
Around 1686, the physiologist Marcello Malpighi examined fingerprints under a microscope. He noted a series of ridges and loops in the earliest scientific treatise on fingerprints. In 1823, another physiologist, Dr. Johannes E. Purkinje, noted at least nine different categories of fingerprint patterns.
In 1858, Sir William Herschel experimented by having someone stamp their palm on the back of a contract, which was received and accepted as valid. This led Herschel to receive credit as the first European to use friction ridge skin officially. The friction ridge is the raised skin of the palms, fingers, and soles of the feet and toes, which aids in grip and leaves fingerprint impressions.
Henry Faulds continued research on friction ridge skin, specializing in its individualization, especially its use as evidence. In 1879, Alphonse Bertillon developed anthropometry. This is the study of body measurements for identification purposes. This biometric method included 11 body measurements. Fingerprints were eventually added to complete the anthropometric records.
Building upon this research, Sir Francis Galton, a cousin of Charles Darwin, studied the minutiae in fingerprints to seek out hereditary traits. Galton used his anthropological laboratories to collect thousands of fingerprints. He authored the first book on fingerprints in 1892.
He listed the three most common fingerprint types: loop, whorl, and arch. Galton identified the uniqueness of friction ridge skin. For example, Galton noted bifurcation in the skin (the point where a ridge in the skin separates into two paths like a fork).
Law Enforcement Begins Using Fingerprint Evidence
With these developments, law enforcement officials soon recognized the potential value of fingerprint evidence. In 1894, Sir Edward Richard Henry, a British official stationed in India, collaborated with Galton on a system for fingerprint classification. Henry created 1,024 primary fingerprint classifications. In Argentina, police official Juan Vucetich also used Galton's findings to create a fingerprint system. Vucetich's work assisted in identifying a murderer in 1892 using thumbprint evidence.
By the beginning of the 20th century, Scotland Yard in London had begun to compile fingerprint information. The police agency used a classification system based on Henry's work to create a Central Fingerprint Bureau. In the United States, the New York Police Department, the New York State Prison System, and the Federal Bureau of Prisons instituted a fingerprint system in 1903. In 1905, the U.S. Army began using fingerprint identification.
The first murder case in the United States that successfully used fingerprint evidence came in 1910 in Illinois. Thomas Jennings was accused of murdering Clarence Hiller after his fingerprints were found at Hiller's house. Jennings appealed his conviction, but the Supreme Court of Illinois upheld the evidence in 1911. Jennings was executed in February 1912. People v. Jennings thus established fingerprint evidence as a reliable standard, formalizing its admissibility.
Use of Fingerprints Today
The Federal Bureau of Investigation (FBI) established a fingerprint repository through its Identification Division beginning in 1924. This repository held fingerprint cards in a central location. Over the next 50 years, the FBI processed more than 200 million fingerprint cards.
In the 1970s, to eliminate duplicate fingerprints and make storing and sharing fingerprints easier among law enforcement agencies, the FBI began using the Automated Fingerprint Identification System (AFIS). The system, developed by outside vendors, computerized the fingerprint card system. In 1992, the former Identification Division transitioned to the Criminal Justice Information Services Division (CJIS). The following programs were then consolidated under the CJIS:
- The National Crime Information Center (NCIC)
- Uniform Crime Reporting (UCR)
- Fingerprint Identification
The FBI introduced the Integrated Automated Fingerprint Identification System (IAFIS) in 1999. IAFIS stores fingerprints from criminals as part of their criminal record. The FBI also runs prints in IAFIS as part of background checks for certain job applicants. This is critical for positions that involve high-level security or handling confidential information, such as:
- Government jobs
- Banking jobs
- Teaching jobs
- Law enforcement jobs
Questions About Fingerprint Identification? Talk to an Attorney
If you're involved in a criminal case as a defendant, you'll want to make sure the evidence used against you is valid and used within the proper context. A criminal history or the existence of your fingerprints at a crime scene does not necessarily prove that you carried out the crime. If you have questions about this or any other aspects of your case, contact an experienced criminal defense attorney near you.