Case study of offender profiling - JOHN DUFFY

Canter applied his criminal consistency theory in order to create an offender profile for the "Railway rapist". 

The offender profile that Canter provided included the following characteristics based on interpersonal consistency:

• male in his mid-late twenties
• poor relationship with women but has probably been married
• considerable sexual experience, potentially with bondage
• a couple of close male friends
• experience with police or knowledge of procedures (he combed the victim's pubic hair to remove evidence of his own)
• probably not physically strong (he used restraints but only enough control to rape)
• male in his mid-late twenties; potentially semi-skilled work

And these were characteristics based on spatial consistency:

• knowledge of the railway
• worked/lived nearby crime scene

These moved John Duffy up the list of suspects to the prime suspect spot due to his extraordinary similarity to the offender profile. 

He was 29 and worked as a travelling carpenter for British rail. He had been married, but was separated. During their time together, Duffy tied his wife up during sex, and the relationship was abusive. He had a criminal record and watched hardcore pornography. He also had two male friends.

(               a)     Describe one case study as an approach to offender profiling (10)

A case study is a piece of research which looks extensively at and documents the development or investigation of one particular event, individual or group. One example of a case study which documents a case of offender profiling is Canter’s case study of John Duffy, the railway rapist.

Canter is a forensic psychologist who devised the criminal consistency hypothesis which is central to the way that many offender profiles are created using the bottom up approach. The criminal consistency hypothesis has two central components: interpersonal consistency, which is the idea that the offender is likely to interact with others in his or her daily life in a similar way to how the victim was treated; and spatial consistency, which refers to how many offenders will commit crimes in places they are familiar with, so it may be en route to their work, or to a friend’s house they visit regularly. In his case study, John Duffy built up the offender profiling upon these principles.

The “railway rapist” was a serial rapist and murderer of several women, who committed these violent sexual acts at railway stations throughout the south east of England during the 1980s. Canter was employed to build up an offender profile in order to significantly narrow down the list of suspects. From the crime scenes, Canter believed that the offender would be in his mid to late twenties, and was likely to have been married though had generally poor relationships with women. The profile also consisted of characteristics such as having an extensive knowledge of the railway systems, a job which involved semi-skilled labour, and previous police contact, judging from the way the bodies were largely clean of any DNA of the offender. Canter also deducted that it’s likely that the offender enjoyed bondage and had considerable sexual experience due to the treatment of the victims, but was likely not to be physically strong.

The offender profile drawn up by Canter was found to be extraordinarily accurate of one man, John Duffy, who admitted to the crimes. He was 29, and had recently separated from his wife. During their marriage, which was abusive, he liked to tie up his wife during sexual intercourse, and he also enjoyed hard-core pornography. Canter had two close male friends, but no female friends. He worked as a travelling carpenter for British rail, and had previous police contact.

Thus, a case study such as Canter’s study of John Duffy, can be used as an effective approach to offender profiling as it gathers in depth data about the crime scene and allows for thorough and extensive profiling to be undertaken.