In the early morning hours of September 19, 1910, Mary Hiller awoke in the Chicago home she shared with her husband and four children. The gas lamp at the top of their staircase, which she always left burning at night, was out – so she sent her husband to investigate.
Upon investigation, Clarence Hiller discovered an intruder: a recently released man named Thomas Jennings. The two struggled briefly before firing several shots, leaving Hiller dead. Prior to this fatal encounter, Jennings had sexually assaulted one of Hiller’s daughters.
Jennings fled, but police apprehended him less than a mile from the crime scene. He was bloodied, with torn clothes and recently shot with a .38 revolver. His explanation for his ragged appearance – that he had fallen from a trolley – was not convincing enough for the police who arrested him.
But it wasn’t just this evidence or eyewitness testimony that ultimately sentenced Jennings to death for murder. These were also the fingerprints he left on a freshly painted railing.
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When did fingerprinting start?
Human fingerprints go back thousands of years, but its first modern use for identification probably originated in colonial India. Around 1860 Sir William James Herschelan employee of the British Indian Civil Service, began experimenting with fingerprints and handprints as a way to sign contracts.
Henry Folds, a Scottish medical missionary to Japan in the 1870s and 1880s, was also fascinated by fingerprints; specifically, he wondered how they could be applied forensically. His first public reflection on it was published in Nature in 1880
Folds shared his ideas in writing with Charles Darwin, who in turn passed them on to his relative, the anthropologist Sir Francis Galton. Galton eventually published three books on such fingerprint concepts, including his 1892 Fingerprints.
Although Galton is also infamous for his eugenics theories, he helped create the basic system of fingerprint patterns—called arches, loops, and spirals—that we still use to uniquely identify someone today.
This system later became the standard for Sir Edward Henry, Chief Commissioner of London’s Metropolitan Police. Following the publication of the Galton-Henry fingerprint classification system in 1900, Scotland Yard formally adopted it in 1901 for criminal records.
Less than a decade later, Jennings left four fingerprints on a freshly painted railing on the back porch outside Hiller’s home. Using the railing to pull himself up, he entered through the kitchen window.
Read more: Why do we have fingerprints?
When were fingerprints first used as forensic evidence?
The morning after the murder, police investigators removed the railing and took enlarged photographs of the prints. They compared those images to two other enhanced sets of fingerprints — one from Jennings’ arrest and another taken months earlier after a parole violation that landed him back in prison.
At the time of the November 1910 trial, fingerprints were already in widespread use in the US for criminal records and identification of federal prison inmates. But their use in courtrooms, particularly in murder cases, was not so widespread.
During Jennings’ trial, prosecutors used expert testimony from four people experienced in taking fingerprints: Michael P. Evans, head of the Chicago Police Bureau of Investigation; William M. Evans, ex-bureau member; Edward Foster, Canadian Police Inspector; and Mary Holland, the first female fingerprint instructor.
The four witnesses personally studied and took thousands of sets of fingerprints and briefed the courtroom on the basics of how the system works. Each expert also testified that the multiple sets of prints at trial were left by the defendant.
Other evidence did not help his case. Jennings’ statements about his injuries and whereabouts were inconsistent with other witnesses’ statements. The bullets from the crime scene were the same as the ones in his revolver. Even the dirt on his shoes matched the dirt left on Hiller’s daughter’s bed.
Fingerprint Analysis: Guilty
On November 10, 1910, the jury returned a unanimous verdict of guilty, with only one person refusing the death penalty. By the third vote, however, this too was unanimous.
Jennings’ attorneys appealed — objecting both to the admissibility of the fingerprints and to the fingerprint examiners being considered experts. The case reached the Illinois Supreme Court in 1911, but there the verdict was upheld: fingerprinting was a science, and expert testimony about it was considered admissible at trial.
A habeas corpus petition claiming that the police violated Jennings’ rights when they forced him to provide fingerprints was denied in the US District Court, and on February 16, 1912, Jennings was hanged.
He is believed to be the first criminal in US history to be convicted based on fingerprints. In the decades that followed, the courts sided with the decision The People v. Jennings as a precedent for the inclusion of fingerprints.
And although there is not proven universally heard in the last century, fingerprints remain an enduring part of forensic investigation alongside more modern techniques.
Read more: A close look at the forensics behind US criminal justice