The "Railway Rapist" attacks 19-year-old Alison Day and abducts her from a London train. Her strangled body was recovered two weeks later. Although the perpetrator had attacked and raped many women since 1982, this was his first murder.
The Railway Rapist had a distinctive method of operation: He used a knife, bound the victim's hands with string, and usually operated close to the railroad tracks. On a single night in July 1985, he struck three times within a few hours.
Public concern caused British police to establish "Operation Hart" to try to locate the criminal. As part of the investigation, Professor David Canter compiled a psychological profile of the assailant, which was still considered to be a cutting-edge technique at the time. Based on his research, Canter hypothesized that the Railway Rapist was a married-but-childless resident of the Kilburn area of London who had a history of domestic violence.
While the investigation was underway, the criminal struck again, raping and killing 15-year-old Dutch schoolgirl Maartje Tamboezer. Police were able to compare results of a forensics test to a list of 5,000 suspects compiled by Operation Hart. John Duffy, an ex-railway employee, was on the list because he had been arrested for other violent offenses at the time. Though he refused to provide investigators with a blood sample, detectives noticed that he closely fit Professor Canter's psychological profile. After examining Duffy's clothes, forensic experts were able to match fibers from one of his sweaters to the fibers found on Duffy's first murder victim. Though he is believed to have been responsible for several other rapes, police were only able to convict him of the murders of Alison Day and Maartje Tamboezer in 1987.
Police also found that Duffy had an accomplice: David Mulcahey, his childhood friend, who was arrested in 1999 and convicted in 2001 for the murders of Day, Tamboezer, and Anne Lock.
Also in 1999, Duffy confessed to nine more rapes and several murders.