The bottom-up approach

• Offender profile emerges based on the data.
• Unlike the US top-down approach, the British bottom-up model does not begin with fixed typologies, instead, the profile is ‘data-driven’ and emerges as the investigator rigorously scrutinises the details of a particular offence.
• The aim is to generate a picture of the offenders’ characteristics, routines and background through analysis of the evidence.
• Statistical procedures detect patterns of behaviour that are likely to occur (or coexist) across crime scenes. This is done to develop a statistical ‘database’ which then acts as a baseline for comparison.
• Features of an offence can be matched against this database to suggest potentiallu important details about the offender, their personal history, family background, etc.
• A central concept is interpersonal coherence- the way an offrnder behaves at the scene (including how they ‘interact’ with the victim) may reflect their behaviour in everyday situations (e.g. controlling, apologetic, etc.); i.e. their behaviour ‘hangs together’ (has coherence). This might tell the police something about how the offender relates to women (for example) more generally.
• The locations of crime scenes are used to infer the likely home or operational base of an offender- known as crime mapping
• Location can also be used alongside psychological theory to create hypotheses about the offender and their modus operandi (habitual way of working)
• The assumption is that serial offenders restrict their ‘work’ to areas they are familiar with- linked to Canter and Larkin.
• Canter and Larkin proposed two models of offender behaviour:

  • The marauder- operates close to their home base
  • The commuter- likely to have travelled a distance away from their usual residence when committing a crime
• Two types of offenders based on location behaviour:

  the commuter and the marauder
• Canter and Larkin suggest that the pattern of offending locations is likely to form a circle around the offender’s usual residence, and this becomes more apparent the more offences there are.
• The offender’s spatial decision-making can provide insight into the nature of the offence (planned or opportunistic, mode of transport, employment status, etc.)
• Strength: wider application

  The bottom-up approach can be applied to a wider range of offences compared to the top-down approach. Techniques (e.g. smallest space analysis, principle of spatial consistency) can be used in the investigation of crimes from burglary/theft to murder/rape. This means that the bottom-up approach is more valuable than the top-down approach as an investigative technique
• Strength: has a scientific basis

  Canter argues that bottom-up approach is more objective and scientific than top-down (more psychological theory and evidence, less speculation and fewer ‘hunches’). Investigators can use geographical, biographical and psychological data to quickly produce data to assist in the investigation. Investigative psychology has also expanded to include areas like suspect interviewing and examination of material presented in court- this supports its use in the judicial process
• Strength: evidence supports geographical profiling

  Lundrigan and Canter 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 was plotted and a ‘centre of gravity’ identified; offender’s base was invariably in the centre of the pattern. The effect was more noticeable for ‘marauders’ (offenders travelling short distances). This supports Canter’s claim that spatial information can be a key factor in determining the base of an offender.
• Limitation: mixed results for profiling

  Despite many successes of the bottom-up approach, there have been significant failures and studies examining its effectiveness have found mixed results. Copson surveyed 48 police forces- advice provided by a profiler was judged ‘useful’ in 83% of cases, but led to accurate identification of an offender in just 3% of cases. This evidence questions the effectiveness of the bottom-up approach.