Fingerprints: characteristics, classification, and forensic applications

Fingerprints are the impressions of the minute ridge patterns found on the fingertips of all individuals. The two basic characteristics of fingerprints are that no two persons have exactly the same pattern of ridge patterns and the patterns remain unchanged throughout a person's life. Because of these unique characteristics, fingerprints offer an infallible means of personal identification and fingerprint identification has become one of the most useful tools of forensic science during the last century and more. In this research paper on fingerprints I shall trace the history of fingerprint identification, discuss why fingerprinting has become the number one identification tool in forensic science, and describe the basic patterns of fingerprints. In addition, I shall also examine certain cases of incorrect fingerprint identification that have thrown doubt on the long-recognized infallibility of fingerprints as an identification tool in criminology.

History of Fingerprints' Use in Identification

Early History: Evidence exists that fingerprints were used on clay tablets in business transactions in Ancient Babylon as long as 3000 years ago and thumbprints were used on clay seals to "sign" documents in China in the 3rd century B.C. This indicates that human beings realized the significance of such patterns, but perhaps did not fully understand, thousands of years before their potential was actually realized. (Meaney, 2006) Wall etchings found in Nova Scotia, Canada, also shows a hand with ridge patterns sketched on it dating from the first century AD and official government documents preserved from the Tang Dynasty in China (610-907 AD) and Persia (14th century AD) have fingerprint impressions on them. In the Persian documents from the same period, one government physician has noted that no two fingerprints were an exact match. (Ibid.)

The Earliest Use of Fingerprints in Crime Solving: The earliest use of a palm print (which is similar in characteristics to a fingerprint) in crime solving was recorded in a murder trial during the Roman Empire when a Roman advocate (circa. 35 A.D.) successfully defended a blind boy accused by his stepmother of murdering his own father. The lawyer proved the boy's innocence by showing a set of bloody handprints on a wall as belonging to the stepmother rather than the boy. (Clegg, 2004, p. 172)

Early Attempts at Explaining the Importance of Fingerprinting: A number of people contributed to the process of development of fingerprinting techniques for identification but it took a long time for fingerprinting to replace the existing method of anthropometry (identification by body measurement) in police work.

In 1684, for example, the Dutch Botanist Dr. Nehemia Grew, wrote a paper on his observations of patterns of the fingers and palms and the arrangements of sweat pores and epidermal ridges without elaborating their practical use ("Every Contact Leaves a Trace..." 2006) In 1686 Marcello Malpighi, an Italian Professor of Anatomy, carried out important research work on fingerprints even though he did not suggest a link between fingerprints and identification. Similarly in 1823, Johannes E. Purkinje, a German Professor of Anatomy, presented a thesis describing nine types of finger patterns; he too did not suggest any use of fingerprints for personal identification. (Ibid.)

The Unrecognized Father of Fingerprints: Perhaps the first person to suggest the use of fingerprints as forensic evidence, but who never quite got the recognition he deserved for his work during his lifetime, was Henry Faulds -- a British surgeon who went to Japan as a missionary and carried out considerable, useful research in medicine during the 19th century. Faulds had a hunch that no two fingerprints were the same and carried out his own research with the help of his Japanese students by taking the fingerprints of as many Japanese and expatriate Europeans as possible and comparing the patterns of whorls and loops and junctions on the fingers. He came to the conclusion that fingerprints could prove useful in criminal investigations as he carried out his own amateur detective work to catch petty thieves who left their fingerprints on bottles and even one left on a wall. (Champkin, 2004) He wrote a letter to the scientific journal Nature published in the issue of October 28, 1880, categorically stating: "When bloody finger marks or impressions on clay, glass, etc., exist, they may led to the scientific identification of criminals." (Zonderman, 1999, p. 78) He also tried to convince police chiefs around the world to use fingerprinting for investigative work and even forwarded his work to Charles Darwin but was summarily ignored.

The Work of Herschel & Galton: Others who were wealthier and better 'connected' than Faulds got greater credit for their work on fingerprints. Sir William Herschel, for example, a British civil servant in colonial India during the mid-nineteenth century, and the grandson of a famous scientist who had discovered the planet Uranus, was recognized for having pioneered the use of fingerprint as an identification tool (Champkin, 2004). In the beginning, though, he had used palm ink-impressions of native Indians as their "signatures" on contracts without realizing their full significance. Over time he began to notice that no two marks looked alike, and the curiously lined patterns on the fingertips never changed since the same persons who signed such contracts after gaps of several years, displayed exactly the same patterns. (Zonderman, 1999, p. 78)

Sir Francis Galton, a cousin of Charles Darwin, picked up Fauld's idea of identification through fingerprints in the 1880s, studied his research, and developed it further. He also collaborated with Sir William Herschel, and was able to provide scientific evidence that no two fingerprints are exactly the same, and that prints remain the same throughout a person's lifetime. He also claimed to have calculated the exact odds of finding two identical fingerprints as 1 in 64 billion. (Meaney, 2006) Galton published his book "Fingerprints" in 1892 in which he detailed the first classification system for fingerprints and identified three types of characteristics, loop, whorl, and arch, for fingerprints; characteristics that are referred to as Galton's Details and are still in use today. (Ibid.)

The First Practical Application of Fingerprinting: Around the same time, the first practical application of fingerprint identification by using fingerprints comparison techniques occurred in another part of the world. The important feat was performed by Juan Vucetich during a murder trial in Argentina in 1892 when he identified that the bloody fingerprints found on a door handle belonged to a woman who had murdered her own children rather than a neighbor who had been falsely accused of the crime. (Clegg, 2004, pp. 162-163) This landmark case resulted in Argentina becoming the first country to replace anthropometry with fingerprinting as the primary means of identification and Vucetich set up the world's first Fingerprint Classification Bureau in Buenos Aires.

Fingerprinting Method of Identification is established: Sir Edward Henry, like Sir William Herschel, was also a member of Indian Civil Service and was posted in the Indian province of Bengal during the colonial days. After visiting Sir Francis Galton in England, Henry returned to Bengal and instituted a fingerprinting program for all prisoners under his jurisdiction. He eventually developed a system of classifying fingerprints, which included 1,024 primary classifications, which became known as the "Henry Fingerprint Classification System." He then persuaded the Governor General of India to adopt fingerprinting as the official method of identifying criminals in British India, which was done in 1897.

Taking the cue from the Indian administration and impressed by the success of the "Henry Fingerprint Classification System" in India, a committee was formed in Britain itself to evaluate the relative merits of the existing anthropometric system of identification and the new fingerprint system devised by Henry. They strongly recommended the adoption of fingerprint system into the Scotland Yard and it was done in July 1901. Henry was also transferred to England where he trained investigators to use the Henry Classification System and within a few years, the System and fingerprinting was established as the uniform system of identification around the world. The "Henry Classification System" is still in use today in most English speaking countries around the globe. ("Every Contact Leaves a Trace..." 2006)

Fingerprinting technology was adopted by the law enforcing agencies in the United States in 1903 and by 1908 it had also been adopted by the U.S. Army, Navy, and the Marine Corps. Large data banks of fingerprints, such as the one collected and stored by the FBI in the U.S. are now standard procedure for identifying criminals in most countries. With the development of computer technology, an Automatic Fingerprinting Recognition (AFR) System, which can automatically scan fingerprints, and recognize the peculiarities of individual fingerprint characteristics have been set up. Such computerized systems of storing and cross-referencing criminal fingerprint records are capable of searching millions of fingerprint files in minutes, and have revolutionized law enforcement efforts. Further advancement in forensic science, such as the development of latent fingerprints by "Superglue" fuming, has enabled more efficient recovery of fingerprints from the scenes of crime and made fingerprinting a vital tool in criminal investigation. ("Every Contact..." 2006)

Why Fingerprinting Has Replaced Other Identification Tools In Forensic Science?

The two fundamental characteristics of fingerprints, i.e., their individuality and permanence, are the basic reason behind their having supplanted other previous methods of personal identification and explain the fact that fingerprints continue to hold their own against other more modern methods of identification such as DNA testing.

Individuality of Fingerprints

In more than 100 years since fingerprint records of individuals started to be collected and compared, no two fingerprints of two different persons, including those of identical twins, have ever been found to be exactly the same. This is not only true for the ridge patterns found on the fingerprints of individuals but also of the patterns on their palms and the soles of their feet. ("The History of..." 2006) Recent studies comparing the fingerprints of cloned monkeys showed that even they have completely different fingerprints. After the introduction of AFIS (Automated Fingerprint Identification Systems), it has become possible to compare the millions of fingerprints data acquired by agencies such as the FBI and such comparisons have not found even a single case of a perfect match of two fingerprints of two different individuals; this further validates the premise about the individuality of fingerprints and gives it the status of a scientific fact.

Permanence

Permanence is one of the key features of fingerprints; it is based on the "Principle of Persistency," i.e., fingerprints are formed during early fetal life, they remain constant throughout life, and are one of the last recognizable features to disappear after death.

Ridges begin to form on the human fetus between the third and fifth months of pregnancy when the fetus is approximately 3" - 4" in length; once the pattern is formed it remains unchanged throughout a person's life. The growth of a person's fingertips along with other parts of the body containing the ridges only expands the pattern uniformly in all directions. Only deep cuts and injuries penetrating all layers of the epidermis can cause the ridge pattern to change; superficial removal of the fingerprint is not permanent as the original pattern reappears in due course.

Previous Methods of Identification

In ancient times, cruel methods such as branding and even maiming were used to mark criminals for their identification. The Romans introduced the method of tattooing their mercenary soldiers for identification purposes and in order to prevent their desertion. ("The History of..." 2006)

For a long period until the mid-nineteenth century, law enforcement officers identified criminals through their visual memories and through eyewitness accounts. Police officers were believed to possess extraordinary "camera eyes" with which they could identify previously arrested offenders by sight but the system had obvious drawbacks. With the advent of photography, the method of identification improved but it was still highly unsatisfactory since appearances of individuals can change drastically with time.

In 1870s, Alphonse Bertillon, a French law enforcement officer created anthropometry-- a system of identification based on physical measurements and record of the dimensions of certain bony parts of the body. The method, which became known as the Bertillon System, was the first scientific system police used to identify criminals but had a major flaw since appearances and sizes could always resemble and could never be absolutely permanent. (Ibid.)

How Does Fingerprinting Compare with DNA Fingerprinting?

Genetic or DNA fingerprinting, discovered in the 1980s is the latest development in forensic science which can, like conventional fingerprinting, can accurately distinguish humans from one another. This method of identification has a number of advantages over all previous methods including fingerprinting, e.g., DNA can be isolated from any part of the body, skin cells, hair, blood, blood stains or semen. Hence, even if a criminal does not leave a fingerprint behind at the scene of crime, he can be identified if his blood, hair, semen etc. is found. A dead body can also be identified from its DNA tests. Like fingerprints, DNA of no two persons can be alike except for the DNA of identical twins, which are alike. Nevertheless, fingerprinting still outperforms DNA and all other systems for identifying criminals and solves ten times more unknown suspect cases than DNA in most jurisdictions around the world. ("The History of..." 2006) This is because there is a huge database of fingerprints available with law enforcing agencies around the world, which can be cross-referenced with the fingerprints of criminals. On the other hand, DNA testing is still relatively new, requires further standardization and quality control to challenge fingerprinting universally as a forensic tool, and there are only a few reliable labs around the world that can give accurate DNA results.

The Basic Patterns & Types of Fingerprints

The patterns on the underside of our fingers and feet consist of some lines that form a continous formation, some are interrupted, others are forked, and still others make formations like pockets and dots. The combination of these formations or patterns is called minutiae and provides the uniqueness of a fingerprint. In the systematic study of fingerprints, these minutiae have been divided into various basic groups. In one of the most widely used systems devised by Sir Edward Henry, the fingerprint patterns are divided into four basic groups:

Arch: a ridge that runs across the fingertip and curves up in the middle, with the tented arches giving a spiked effect.

Whorl: an oval formation which makes a spiral pattern around a central point.