On the morning of March 27, 1905, London shopkeeper Thomas Farrow awoke to the sound of knocking on the front door of the business he managed, Chapman’s Oil and Colour Shop. Though it was 7 a.m.—much earlier than his opening time—Farrow wasn’t about to turn down a little extra business. So he rose from bed, still clad in his pajamas, and answered the door to two men who seemed intent on getting an early-morning browsing session through Farrow’s supply of paints and brushes. It didn’t take long for Farrow to realize that he wasn’t dealing with a pair of anxious artists.

Shortly after opening the door for them, the two men made it clear to Farrow that they were there for his money. When he resisted, they proceeded to attack him, striking him at least a half-dozen times over the head with a blunt instrument. Though Farrow did his best to prevent the men from advancing beyond the storefront, they were able to make their way upstairs, where they found the money that they had come for (a sum that totaled less than $15) and Farrow’s wife, Ann, whom they also brutally attacked.

An hour later, Farrow’s teenaged assistant, 16-year-old William Jones, reported for work and was surprised to find that the door was locked. He went to another one of Chapman’s companies and came back with an assistant. Together, they got into the shop by means of a back door and found Thomas Farrow’s lifeless body.

After alerting the authorities, Sergeant Albert Atkinson arrived on the scene and made his way into the house and up the stairs, where he found Ann, who was badly injured but still breathing (like her husband, she had sustained several blows to the head). She was rushed to the hospital, but it was too late; several days later, she succumbed to her injuries, leaving no eyewitnesses to the crime. And no murder weapon had been found.

What police did have was an empty cash box with a bloody fingerprint, which indicated to them that the motive had been robbery. There were also two people who claimed to have seen two men leaving the Farrows’ shop around 7:15 a.m. that morning: two milkmen, who were able to give police a very detailed description of what the men were wearing. A third witness was able to identify 22-year-old Alfred Stratton as being in the area at the time.

Though Stratton did not have a criminal record, he and his brother Albert were well known to the police for associating with the wrong element.

When questioned, Alfred’s girlfriend confirmed that her boyfriend did own the outfit that the witnesses had described, and that he was wearing it the morning of the murder—but that he gave the clothes away that same day. For her part, Albert’s girlfriend (who said she was "in a family way by him") told police that when her beau had come home that morning, he smelled of paraffin, which she told him, and had an unexplained wad of cash on him.

On April 2, police arrested Alfred at the King of Prussia pub in Deptford; Albert was arrested the next day, not far from the Farrows' home.

When the milkmen were unable to confirm that the Stratton brothers were indeed the two men they saw leaving the Farrows’ shop, it seemed as if the case would have to be built on purely circumstantial evidence. What the two young suspects didn’t realize was that the police had been able to lift a thumbprint from the Farrows’ cash box, and that they had a relatively new investigative technique on their side: fingerprint analysis.

It was only four years earlier that Scotland Yard had begun to understand how powerful a piece of evidence a matched fingerprint could be to a criminal case, and so assembled an entire department whose sole task was to focus on fingerprint analysis.

When the Strattons appeared in court six weeks after the crime, their trial became as much about showcasing what fingerprint evidence could offer law enforcement investigating crimes as it was about proving the two men guilty. Though fingerprint evidence had been cited in murder cases in Argentina in 1892 and India in 1898, it was still a largely untested—and as such, untrusted—methodology. By the time the Stratton case was brought to trial, fingerprint evidence had first been used 3 years earlier to solve a burglary, but had never been used on a high profile case like this. Because it was such a relatively new concept, skeptics were not yet convinced that a single fingerprint could be of any value to investigators (as opposed to, say, all 10 fingers).

And so the burden of proving that Alfred Stratton’s thumbprint at the murder scene was indeed proof of his and his brother’s guilt in committing the crime was placed on the prosecution’s shoulders. And they ran with it.

The defense put its own expert, Dr. John Garson, on the stand in order to throw up several red flags as to the reliability of fingerprint evidence. But the prosecutor was able to counter (and prove) that Dr. Garson had offered his professional services to the prosecution team’s argument as well, thus making his testimony wholly unreliable.

When called to present evidence in the case, Detective Inspector Charles Collins explained to the jury: “At Scotland Yard we have now between 80,000 and 90,000 sets of fingerprints, which means between 800,000 and 900,000 impressions of digits—in my experience I have never found any two such impressions to correspond.” He then presented enlarged images of the thumbprint found at the scene and the print taken from Alfred, and pointed out the characteristics that made it clear they were from the same person.

The jury was convinced. It took them just two hours to find the Stratton brothers guilty of the murders of Thomas and Ann Farrow. The case became well known, and led law enforcement agencies worldwide to begin looking for (and at) fingerprints as a way to prove an array of crimes. In 1910, fingerprints pointed to a killer for the first time in the United States when Thomas Jennings was found guilty of the murder of Clarence Hiller in Chicago.

On May 23, 1905, Alfred and Albert Stratton were hanged at Wadsworth Prison.