Born in 1959, John Duffy was a British serial killer who murdered multiple women the 1980s in partnership with his childhood friend David Mulcahy. The concept of psychological offender profiling, which was evolving at the time, helped police catch Duffy. He revealed his accomplice ten years later.
John Duffy was a brutal rapist and killer who struck lone women at railway stations throughout the southeast of England and London.
He was at first thought to have carried out his heinous crimes alone and was sentenced to life imprisonment for the murders. But police were sure that Duffy had an accomplice.
Only after 15 years did the advances of forensic science allow authorities to arrest David Mulcahy, a childhood friend of Duffy, who was eventually convicted.
Today Mulcahy still maintains his innocence, insisting that Duffy implicated him in the murders.
John Duffy and David Mulcahy had been lifelong friends since their days together at school in north London.
They both shared an early sadistic streak for tormenting and torturing animals starting with a hedgehog, which Mulcahy beat to death with a plank when he was just 13.
As they got older the boys began to transfer their sadistic and misogynistic tendencies to women, fuelling each other's dark sexual fantasies.
It is baffling to understand how a young friendship could have degenerated into a secret life of violence, rape, and murder. One theory is that bullying, which both Mulcahy and Duffy endured as schoolboys, may have been a key factor in driving them to rape and kill.
Whatever the trigger, the two boys had developed a severely psychotic side to their personalities at an early age. As he grew older, Duffy married and became a martial arts fanatic.
Their brutal crimes began on July 1, 1982, when the pair attacked and violently raped a 23-year-old woman in north London. Over the next four years 18 more women would be attacked.
Despite John Duffy's police record—he assaulted his wife and was found carrying a knife - he was still able to carry out a string of sexual assaults and commit two murders over a 15 month period.
On July 1, 1982, Duffy and Mulcahy attacked and raped a woman close to Hampstead Station in London's Hampstead village.
The assault gave the two psychopaths a taste for terrorizing women in similar scenarios and for the next 12 months women were assaulted across London and its suburbs.
In all, 18 women were raped near various train stations, as well as in an area close to Duffy's Kilburn house.
The police set up an urgent workshop to try to find the perpetrators, called Operation Hart. It was the largest investigation to take place in the U.K. since the Yorkshire Ripper investigation a few years earlier.
In Autumn 1983 the attacks suddenly stopped. Police later found out that this coincided with Duffy's separation from his wife.
Early in 1984 the attacks began again, this time in west London and north London. The police had no evidence to link the crimes and were unsure as to whether they were committed by the same man, or two different individuals.
Then, in July 1985, three women were raped on the same night, all in the Hendon and Hampstead area. Duffy and Mulcahy were pulled in for interrogation, but were eventually released. However, in August 1985, after a bout of domestic violence at his home, where he attacked his wife, Duffy was arrested.
He was interviewed and eventually added to the Hart computer system as one of many thousands of men being investigated. Unfortunately Duffy was far down the list of suspects. Mulcahy, who was Duffy's accomplice in the rape attacks, was also questioned and eventually released.
A new concept in crime investigations, called psychological offender profiling, was evolving at the time.
Professor David Canter from Surrey University was called in to aid the police investigation and it was his profiling system which helped crack the case.
Canter drew up a list of 17 personality and characteristic traits, including environmental clues that the offender may display. When Duffy was finally caught, Canter was proved correct on at least 12 of these traits.
In September 1985, a woman was attacked in Barnet. The description of the attacker fit Duffy and the police pulled him in for questioning and placed him in an identity parade. However, the victim, still traumatized from the assault, failed to pick him out.
Mulcahy was also questioned but eventually released. It was a grave mistake, costing the lives of several women.
On December 29, 1985, Alison Day, 19, was dragged off a train by Duffy and Mulcahy, and raped repeatedly. She was then strangled with a piece of string.
This was the first time the victim had been killed. Police stepped up their search for the attacker. The death of Day changed the attacker's moniker from the Railway Rapist to the Railway Killer. There was still no evidence at this time to suggest that two men were carrying out the attacks.
In the spring of 1986 the two men attacked another helpless young victim. Fifteen-year-old Maartje Tambozer was abducted from Horsley station in East Surrey on April 17, 1986. After being raped and strangled, the teenager's body was set on fire, most likely a grisly attempt to destroy any evidence.
Less than a month later, on May 12, 1986, Duffy was arrested after he was found carrying a knife. However, there was not enough evidence to charge him and he was released—only to kill again six days later.
On May 18, the victim was local TV presenter Anne Locke, 29, who was abducted as she disembarked from her train in Hertfordshire.
In October 1986, a 14-year-old schoolgirl miraculously managed to get away with her life after she was raped by both men.
After this attack, on October 21, Duffy's luck began to run out. While stalking a woman in a park on November 7, he was discovered and arrested. The next day, Duffy was charged with three murders, and seven counts of rape.
Mulcahy was also arrested, but later released due to lack of evidence. It would be two years before Duffy would speak out and admit that he carried out the attacks with an accomplice.
Trial and Aftermath
Duffy went on trial in February 1988 and was convicted of two murders and four rapes, though he was acquitted of raping and killing Anne Locke.
He was given a minimum sentence of 30 years by the judge, later extended to a whole life sentence by the Home Secretary. This was rescinded by a European Court of Human Rights ruling, that later removed the right of politicians to reset sentence lengths.
Duffy kept silent about having an accomplice until he decided he wanted to clear his conscience while undertaking a counseling session.
He chose not to reveal any more information about his partner in crime until nearly 15 years later in 1997 when he implicated Mulcahy. The police had suspected Mulcahy for years but had no evidence on which to convict him until Duffy's confession.
Duffy also admitted his involvement in the attack on Anne Locke, although he couldn't be retried under the double jeopardy rule.
However, Mulcahy, a married father of four—had been tracked for several months by police prior to his arrest. DNA tests, which were not yet in use during the original investigation, finally proved his involvement conclusively.
In 2000, Duffy appeared at in court as a witness against Mulcahy and gave detailed and graphic evidence over 14 days. It was the first time a highest-category prisoner had ever given evidence against an accomplice.
Mulcahy emerged as the chief perpetrator of the crimes and the first to decide that sexual stimulation was no longer enough of a thrill, leading the pair to turn to murder. He was said by a former employee at a cab firm he worked at to despise women.
"He liked women to be at the kitchen sink where they should be, or in bed," said Lola Barry, a controller at the cab firm.
She said Mulcahy had once crept up behind her in the office.
"He actually got me round the neck, saying 'How does that feel—are you scared?'"
Prosecutor Mark Dennis said in Mulcahy's trial, "As they fed their newfound predilections they treated their victims as objects rather than persons." It was "only a comparatively small step" between the violence of the rapes and the murders—and Mulcahy was the first to take that step.
"He was the instigator and prime mover in the murders, and the one for whom the sexual abuse had become insufficient to satisfy," said Mr. Dennis.
In the witness box, Duffy catalogued their heinous campaign of rape and murder, describing how the two friends would go out on "hunting parties" in the '80s searching for women. Duffy used his knowledge of the rail network to target his victims and drag them into concealed areas where they could be attacked.
"We would have balaclavas and knives," Duffy claimed. "We used to call it hunting. We did it as a bit of a joke. A bit of a game."
Mulcahy protested his innocence, but on February 5, 2001, was given three life sentences for murdering three women. He also received 24-year jail terms on each of seven counts of rape and 18 years each for five conspiracies to rape, to run concurrently.
The police believed that the two men were probably responsible for more deaths and sexual attacks and reinvestigated the 1980 murder of Jenny Ronaldson, 19, who was sexually assaulted, strangled and thrown in the Thames.
Apart from the level of ferocity associated with this case, the Duffy/Mulcahy casebook is one of the most significant criminal cases for its first use in England of psychological offender profiling.
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