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. 

Creating a Profile - Bottom-up Approach

The British police take a different approach to offender profiling to the FBI.

• It's based on psychological theory, rather than police experience. 
• One key theory is the "criminal consistency hypothesis". This is Canter's theory that criminals act in a consistent manner, and thus the characteristics they displayed in their crime are likely to be similar to how they are in their everyday lives. 
1. Interpersonal consistency: how the offender treated the victim may be characteristic of their approach to that race/culture/sexual orientation/gender. E.g. rapists may be aggressive to female co-workers.
2. Spatial consistency: the offender is likely to commit somewhere that they are comfortable in - somewhere they know well. e.g. a murder may be committed en route to a friend's house or their workplace.
• It's based on patterns and objectivity, so it's often referred to as quantitative. 
• It's appropriate for a wider range of crimes than the FBI approach, but works best for crimes such as murder and rape.
• It's called the bottom-up approach because the police look at details and use this to gradually build up the profile, whilst the top-down approach attempts to fit crime scenes under pre-existing categories. 

Study: Copson conducted a study using detectives from 48 police forces in the UK. The study used self-report to gather data on the opinions on and potential for offender profiling. The results showed that a minority of detectives found profiling useful in solving the case, but that a fair number would use profiling again. It was concluded that offender profiling was effective in providing a valuable second opinion or supporting what the detectives thought, and suggested that better education in the theory behind profiling may develop trust in profiles. 

Creating a Profile - Top down approach

This is potentially one of the more difficult areas to get your head around in G543 forensic psychology. Here's a simplified version that can help you with your 10-markers:

• The top-down approach is also referred to as "crime scene analysis", "typological profiling"and "the FBI approach".
• It's American (used by the FBI).
• It was based on a small number of case studies of offenders, which essentially categorized offenders and crimes into organised or disorganised:
• Organized crime scenes are generally characterized by no visible evidence or weapon. They're planned in advance, thoughtful and not spontaneous. The body may be hidden, or moved from the original location. It reflects control, and restraints may have been used and brought with them. Organized offenders are thought to be of above average intelligence, socially and sexually competent, may be in a relationship, and was likely to be depressed or frustrated at the time of the murder.
• Disorganized crime scenes tend to be the result of spontaneous crimes. Little or no effort has been made to remove evidence, and crime scenes show lack of control. Disorganized offenders are likely to live or work nearby the scene, live alone or with parents, be of low birth order status, not be in a stable relationship, and of average or below average IQ.
• It's described as a qualitative approach to offender profiling due to looking at the overall picture and using typologies. 
• It's based on police experience and case studies rather than psychological theory.
• It's suitable for the more extreme/unusual crimes, such as murder, rape and ritualistic crimes. 

N.B. Whilst it was based on case studies of actual offenders, studies have suggested that this may not be a reliable way to create accurate offender profiles. For example, Mokros and Alison used a sample of 100 rapists, and found no correlation between aspects of crime scenes and characteristics of the offender. This suggests that socio-demographic profiling may be too reductionist.