The Mystery of the Invisible Prints

Have you ever wondered how fingerprints became the standard for unique identification? In the past, investigators relied on various physical traits like names, facial measurements, and body proportions, including height, arm span, and finger length. Despite these detailed methods, they failed to reliably distinguish individuals. However, one pivotal incident led to the widespread adoption of fingerprints as the primary method for identification.

Historical records suggest that as early as 200 BC, fingerprints were used in China as signatures for legal documents and trade agreements. Though they weren’t analyzed at the time, this practice indicated that fingerprints were recognized as unique to individuals. Fast forward to 1686, Dutch physician Govard Bidloo described fingerprints in his book The Anatomy of the Human Body, but he did not claim they were unique. Later, his work was plagiarized by English surgeon William Cowper. In 1823, Evangelista Purkinje classified fingerprints into nine main patterns and discovered sweat glands, yet he too did not conclude that fingerprints were distinct for every person.

A major breakthrough came in the 1870s when British physician Henry Faulds, while on an archaeological dig, noticed unique fingerprint impressions in ancient clay pottery. Upon examining his own fingerprints and those of his colleagues, he became convinced of their uniqueness. His theory was tested when his hospital was burglarized. The police arrested a suspect, but Faulds compared the fingerprints left at the crime scene with those of the accused and proved they didn’t match. This evidence led to the suspect’s release, and Faulds published his findings in Nature, seeking support from Charles Darwin. However, Darwin declined, and Scotland Yard dismissed the idea due to insufficient proof and their preference for the existing Bertillon system.

The Bertillon system, developed by Alphonse Bertillon in 1879, was a method of criminal identification based on detailed body measurements, including head length, finger length, and foot length, combined with photography (now known as the mugshot). Though considered scientific, it had flaws, primarily the assumption that skeletal structure remains unchanged after the age of 20. The system remained in use for nearly 30 years until a major event in 1903 exposed its limitations.

In 1892, Francis Galton—Charles Darwin’s cousin—published Fingerprints, which laid the foundation for modern fingerprinting. He described fingerprint patterns, collection methods, and analysis techniques, concluding that fingerprints remain unchanged throughout a person’s life and that no two are identical. However, he failed to credit Henry Faulds for his foundational work. Meanwhile, in Argentina, Juan Vucetich made the first successful criminal conviction using fingerprint evidence when a woman attempted to cover up her murder of her two children by blaming an outsider.

In 1901, Sir Edward Henry, an inspector general of police in Bengal, India, developed the first systematic fingerprint classification method, which became the official identification system in England and later spread worldwide.

The Bertillon system's credibility collapsed in 1903 when a man named Will West was sent to Leavenworth Penitentiary in Kansas. His physical measurements and facial features matched exactly with an inmate already serving a life sentence for murder—William West. The prison clerk was bewildered by the identical features and double-checked the records. Since the two men appeared indistinguishable by Bertillon’s method, authorities fingerprinted them, revealing that their prints were completely different. This event proved the reliability of fingerprints over body measurements and led to fingerprinting replacing the Bertillon system.

By 1911, fingerprint evidence was officially accepted in the United States. Thomas Jennings became the first person convicted of murder using fingerprints. His defense challenged the reliability of the method, prompting prosecutors to lift his fresh prints from a document he had just touched. When the prints matched, the jury was convinced, leading to his conviction and execution in 1912. The Illinois Supreme Court upheld the use of fingerprint evidence, solidifying its role in criminal justice.

Today, forensic experts use fingerprint powders to detect prints at crime scenes. The powder clings to the oils left by fresh fingerprints, making them visible. Analysts examine characteristics such as ridge patterns and depth, verifying their findings before confirming a match. Advanced technology has further enhanced fingerprint analysis, with ultrasonic sensors in smartphones creating 3D fingerprint models for authentication. Law enforcement agencies now use automated fingerprint identification systems (AFIS) to rapidly search through digital fingerprint databases.

Despite its long journey to widespread acceptance, fingerprinting has become an essential tool in modern identification, used in everything from cybersecurity to criminal investigations. While many credit Francis Galton as the father of fingerprinting, others believe Henry Faulds deserves that title for his pioneering work.