Module 5 - Criminal Profiling

John Duffy was a violent rapist who embarked upon a four-year crime spree in 1982, attacking lone women near railway stations throughout various neighbourhoods in London, England. It was first thought that he had committed these crimes by himself, but police eventually concluded that he had an accomplice. They would be unable to establish sufficient proof until 1997, when Duffy admitted that David Mulcahy, a childhood friend, had been involved from the very beginning.

The First Attacks

The first sexual assault occurred in July 1982 when the yet to be identified Duffy and his accomplice attacked and raped a 23-year-old woman near a train station in a neighbourhood outside North London. Eighteen more attacks occurred, mainly at night, near various railway stations in the London area. Most victims were teenage girls attacked while waiting for their train to arrive.

When investigators became convinced that two individuals appeared to be responsible for the violent sexual assaults that terrorized the citizens of London, the pair became known as the Railway Rapists. It was later discovered that most of the crimes occurred as close as a five-minute walk from Duffy's house.

Operation Hart

In July 1985, three women were raped on the same night, all within a neighbourhood in North London. The police quickly set up a Task Force, calling it Operation Hart. It was the largest multi-jurisdictional police investigation in the United Kingdom since the Yorkshire Ripper investigation was concluded successfully several years before.

In August 1985, Duffy happened to be arrested after assaulting his wife. His name was eventually added to the Operation Hart computer system as one of many thousands of local men who were being investigated as possible suspects.

In September 1985, another vicious sexual assault occurred. Police thought the attacker’s description resembled Duffy. He was brought in for questioning and even participated in a photo line-up. The victim was unable to identify him as the assailant, perhaps due to the traumatic stress she experienced during the crime.

The First Murders

On December 29, 1985, Alison Day, aged 19, was dragged off a train at Hackney station and repeatedly raped by Duffy and Mulcahy. She was then strangled to death with a piece of rope. This was the first time the two men had killed one of their victims, and police increased the intensity of their efforts to identify the culprit. Day’s murder meant that Duffy would now be referred in the media as the Railway Killer. Yet, still no physical evidence was available to suggest that two men were carrying out the attacks.

In April 1986, a fifteen-year old female was abducted from a train station in East Surrey. The teenager’s body was set on fire after she was raped and strangled, likely to try to eradicate any physical evidence that could identify the attacker.

Duffy was arrested near a local train station less than a month later—this time for the illegal possession of a knife. However, he was released without charge due to a lack of evidence, only to murder another person a week later. In May 1986, Anne Locke, an employee of a local TV station, was abducted as she arrived at a train station just outside London. Her body was found two months later, and the analysis of traces of semen found in her body confirmed that the individual known as the Railway Killer was responsible.

In the meantime, police continued to interview each of the nearly 5000 men who had been added to the Operation Hart database, requesting a blood sample at the time of each interview. This voluntary process likely was offered to each individual as a means of clearing any doubts about guilt or innocence. Duffy was interviewed on July 17, 1986, but he refused to participate voluntarily in the blood test at that time. He then committed himself to a mental hospital, perhaps as a means of covering his tracks.

The Use of Criminal Profiling

By July 1986, police were desperate to identify the person or persons responsible for this string of horrible crimes. Consequently, they requested the assistance of Dr. David Canter, an expert in behavioural science and professor of applied psychology at Surrey University. At this time, a new concept in criminal investigations was being introduced, referred to by Dr. Canter as “Psychological Offender Profiling” (also known as criminal profiling). This was the first murder investigation in England in which criminal profiling had a significant role. John Duffy, who would later be identified as the Railway Killer, was the first person in the history of the English justice system to be identified as a suspect as a direct result of this investigative technique.

To help solve the case, Dr. Canter analyzed large numbers of solved crimes using a statistical technique known as multivariate analysis. In each case, the behaviour of the criminal (including the choice of victims, personal interaction with them, location and timing of each offence, and content analysis of their speech) was used as a data source. As Dr. Canter examined the details of each crime, he was able to build a profile of the attacker's personality, habits, and traits.

He then created a profile based on witness statements, crime scene reports, and geographical information. He produced a list of seventeen personality and characteristic traits including environmental clues that the offender might display. For example, he was able to infer that the killer lived in an area of northwest London and had an unhappy married life with no children. Interestingly, Canter relied on his background in environmental psychology to develop concepts such as the cognitive map, which would prove useful in understanding offender behaviour. In fact, his research found that most British serial rapists lived within the area in which they committed their crimes.

Below is an abbreviated list of points Canter believed would fit the offender’s profile:

Duffy Becomes Main Suspect

As the process of creating an offender profile ended, a fourteen-year-old schoolgirl was raped in a park in October 1986. When the psychological profile created by Dr. Canter was cross-referenced with the police database of all possible suspects, the computer generated a match for John Duffy.

Duffy was placed under police surveillance. He was arrested on November 7, 1986, when he was seen stalking a woman in a park. He was questioned about his involvement in the numerous rapes and murders committed over the past four years. He offered a weak alibi involving tales of amnesia. With sufficient forensic evidence to support a successful prosecution, Duffy was charged with three murders and seven counts of rape. Police suspected that he had not committed the offences alone, but Duffy refused to cooperate any further.

Dr. Canter’s profile of the killer was accurate in 13 of 17 points. He attributed the success of his technique to an understanding of how a criminal leaves behind ‘evidence of his personality’ through his actions in relation to a crime, including specific behaviours characteristic of that person. Consistent behaviours typical of the person’s social group also provide information that can be used to develop a profile.

According to Dr. Canter, to build a profile of an offender from ‘the bottom up’ is possible. By reviewing a wide range of associated factors and operating under the premise that people behave typically consistently, the analysis of behaviour patterns observed over time can provide clues about a serial offender’s ordinary behaviour.

Conclusion

Duffy went to trial in February 1988. He was convicted of two murders and four rapes, but he was acquitted on the remaining charges, including the murder of Anne Locke. Duffy later revealed to a psychologist that he had not been working alone when he committed his heinous crimes. However, he revealed no further details until 1997 when he implicated childhood friend David Mulcahy, a married father of four who was later convicted and sentenced to life in prison. This marked the end of the lengthy and determined search for the Railway Killers, one that made effective use of criminal profiling.