Since the cash box in which the Farrow's stored their cash receipts was empty, it was clear to Scotland Yard investigators that robbery was the motive for the crime. One print on the box did not match the victims or any of the still-tiny file of criminal prints that Scotland Yard possessed. Fortunately, a local milkman reported seeing two young men in the vicinity of the Farrow house on the day of the murders. Soon identified as brothers Alfred and Albert Stratton, the police began interviewing their friends.
Alfred's girlfriend told police that he had given away his coat the day and changed the color of his shoes the day after the murders. A week later, authorities finally caught up with the Stratton brothers and fingerprinted them. Alfred's right thumb was a perfect match for the print on the Farrow's cash box.
The fingerprint evidence became the prosecution's only solid evidence when the milkman was unable to positively identify the Stratton’s. The defense put up expert Dr. John Garson to attack the reliability of the fingerprint evidence. But the prosecution countered with evidence that Garson had written to both the defense and prosecution on the same day offering his services to both. The Stratton brothers, obviously not helped by the discrediting of Garson, were convicted and hanged on May 23, 1905. Since then, fingerprint evidence has become commonplace in criminal trials and the lack of it is even used by defense attorneys.