bottom up approach Flashcards
Intro
The bottom up approach was largely developed in Britain, and is closely associated with the work of David Canter.
Aim is to generate a picture of the offender through evidence analysis.
• Characteristics
• Routine behaviour
• Social background
No fixed typologies-profile is data driven
Investigative psychology
An attempt to apply statistical procedures and psychological theory to the analysis of crime scenes.
Aim is to establish patterns of behaviour that are likely to occur across crime scenes.
Creation of a database, as a baseline.
• Details of a crime can then be matched to the database → same offender?
• Interpersonal coherence
• Time and Place
• Forensic awareness.
Interpersonal coherence
Interpersonal Coherence
• The way the offender behaves at the scene inc. the way they interact with the victim.
Time and Place
• Could indicate something about where they live or work.
Forensic awareness
• Behaviour could indicate that they have been involved with the police in the past.
Geographic profiling
Uses information about the location of linked crime scenes to make inferences about the likely base of an offender.
• Spatial consistency - offenders will stick to a certain area → centre of gravity becomes clear.
• Circle Theory (Canter and Larkin, 1993)
The distribution of offences allows us to describe offenders in one of 2 ways.
• Marauder - Operates in close proximity to home base.
• Commuter - Travelled a distance from their usual residence.
This could provide insight into the nature of the offence. Planned/opportunistic; mode of transport; age; employment status.
The railway rapist-John Duffy
David canter made his name after assisting police in the capture of John Duffy, the railway rapist, in the 1980s.
• 24 sexual attacks and 3 murders
• Canter analysed geographical information from the crime scenes and combined with details of similar attacks.
Canter’s profile:
Lives in Kilburn
Marriage problems
Physically small, unattractive
Martial artist
Need to dominate women
Fantasies of rape, bondage
True facts about Duffy:
Lived in Kilburn
Separated
5ft 4in with acne
Member of martial arts club
Violent - attacked wife
Tied up his wife before sex
Strength-evidence for investigative psychology
One strength of investigative psychology is that evidence supports its use.
David Canter and Rupert Heritage (1990) conducted an analysis of 66 sexual assault cases. The data was examined using smallest space analysis and several behaviours were identified as common in different samples of behaviour, such as the use of impersonal language and lack of reaction to the victim.
Each individual displayed a characteristic pattern of such behaviours and this can help establish whether two or more offences were committed by the same person.
This supports one of the basic principles of investigative psychology, that people are consistent in their behaviour.
Strength-evidence for geographical profiling
Lundrigan and Canter (2001) collated information from 120 murder cases involving serial killers in the US. Smallest space analysis revealed spatial consistency in the behaviour of the killers.
• The location of each body disposal site created a centre of gravity,
• Offenders start from their home base they go in different directions each time they dump body, but in the end this creates a circular effect around the home base.
• The offenders base was invariably located at the centre of the pattern
• Especially with marauders.
This supports the view that geographical information can be used to identify an offender.
limitation-geographical information is insufficient
As with investigative psychology, the success of geographical profiling may be reliant on the quality of data that the police can provide.
• Recording of crime is not always accurate; Can vary between police forces; estimated 75% of crimes are not even reported to the police in the first place.
• Makes us question the use of an approach that relies on the accuracy of geographical data.
• Critics also claim that other factors are just as important in creating a profile, such as the timing of the offence and the age and experience of the offender (Ainsworth 2001)
This suggests that geographical information alone may not always lead to the successful capture of an offender
Final thoughts
The success rates for offender profiling and the views of police forces who have used the techniques suggest that what profiling can’t reliably do is identify an offender.
• It is a tool for narrowing down possibilities, not one that provides exact answers.
• There is a danger is sticking too closely to the profile.
• Rachel Nickell - stabbed 47 times and sexually assaulted on Wimbledon Common in 1992.
• Profile led to the wrong man being arrested.
While an offender profile can be helpful in narrowing down possibilities it must be used with great caution to avoid wrongful arrest and convictions.
6 Marker
The bottom-up approach was largely developed in Britain and does not use fixed typologies like the top-down approach, but rather is data driven and evidence analysis to produce a profile.
Two examples of bottom-up methods are investigative psychology and geographical profiling. Investigative psychological attempts to apply statistical procedures and psychological theory to the analysis of crime scenes in order to establish patterns of behaviour that are likely to occur across difference scenes. There are three main features of this method. Interpersonal coherence, which refers to the way the offender behaves at the scene. The analysis of the time and place of the offence. And forensic awareness, which refers to behaviours that indicate whether or not the have been involved with the police in the past.
Geographic profiling uses information about the location of linked crime scenes to make inferences about the likely home or operational base of an offender. It is based on the idea of spatial consistency, which suggests that serial offenders will restrict their work to geographical areas that they are familiar with. Understanding the spatial pattern of their behaviour allows investigators to determine a centre of gravity for the offender, which is likely to be or be near a base of operations.
