Offender Profliling

• Top-down Typology:

  Starts with the big picture and fills in the smaller details later.
• Who created the Top-down approach and when?

  Created in the 1970s by FBIs Behavioural Science Unit.
• The Top-down approach was based off research on 36 sexually motivated serial killers.
• The four main stages in Top-down offender profiling are…

  - Data assimilation

  - Crime scene classification

  - Crime reconstruction

  - Profile generation
• Hazelwood and Douglas (1980)

  Published their account on the ‘lust murderer’. They theorised two types of murderers: organised and disorganised. Example of Top-down typology.
• Organised Murderer

  - Crime is planned

  - High IQ

  - Weapons and restraints bought to crime scene

  - Little evidence left
• Disorganised Murderer

  - Little planning

  - Little attempt to hide evidence

  - Low IQ

  - Sexually and socially inadeuqte
• Top-down psychology can only be applied to sexually motivated serial killers because of the original sample from the FBI (36 sexually motivated killers).
• Alison et al (2002)

  Suggests Top-down approach is based off of outdated theories of personality being stable. External factors can be a major influence.
• The Top-down approach is too reductionist. Offenders can’t always be classified as organised or disorganised.
• Bottom-up Typology

  Created by Canter (1990). No initial assumptions made and relies heavily on computer databases.
• The Railway Rapist

  John Duffy carried out 24 sexually motivated attacks and 3 murders of women near North London railway stations. David Canter used the Bottom-up approach to create an offender profile for him.
• John Duffy Offender Profile

  The profile was accurate the system suggesting correctly Duffy…

  - Lived in Kilburn

  - Had marriage problems

  - Was a martial artist

  - Liked to dominate and restrain women
• The Bottom-up profile of Duffy didn’t directly lead to his arrest.
• Smallest Space Analysis

  A computer program that identifies patterns in series of crimes to find potential links.
• Interpersonal coherance

  The behaviour of the offender at the crime is the same as their behaviour in everyday life.
• Geographical profiling

  Used to make inferences about where the offender is likely to live based on the locations of their crime.
• Spacial Consistency - Circle Theory

  Made by Canter (1993).

  Consists of marauders and commuters.
• Marauders

  Commit crimes close to where they live so they feel secure. Usually disorganised criminals.
• Commuters

  Commit crimes away from where they usually live. Usually organised.
• Canter and Heritage (1990)

  Analysed 66 sexual assault cases using the Smallest Space Analysis and identified clear common patterns of behaviour.
• Lundrigan and Canter (2001)

  Collated evidence from 120 murderer cases and found that the offenders home base was invariably located in the centre of the crime scene pattern.
• Bottom-up approach is scientifically robust, through the use of the Smallest Space database.
• Bottom-up approach has wider applications than Top-down typology. It can be applied to other crimes, not just sexually motivated ones.
• Copson (1995)

  83% of police forces found Bottom-up profiles useful but in only 3% did it lead to the accurate identification of the offender.