bottom-up approach (offender profiling)

• bottom-up approach definition

  • profilers work up from the evidence collected from the crime scene to develop hypotheses about the likely characteristics, motivations and social background of the offender (offender profile emerges based on data)
  • British approach
• investigative psychology (IP) definition

  • a form of bottom-up profiling that matches details from the crime scene with statistical analysis of typical offender behaviour patterns based on psychological theory
• statistical (smallest space) analysis (IP)

  • 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 potentially important details about the offender, their personal history, family background etc
• analysis based on psychological concepts (IP)

  • interpersonal coherence = the way an offender behaves at the scene (including how they 'interact' with the victim) may reflect their behaviour in everyday situations (eg, controlling, apologetic etc.) ie their behaviour 'hangs together' (has coherence)
  • significance of time and place = may indicate where the offender is living (as in geographical profiling)
  • forensic awareness = those individuals who have been the subject to police interrogation before; their behaviour may denote how mindful they are of 'covering their tracks'
• geographical profiling (GP) definition

  • a form of bottom-up profiling based on the principle of spacial consistency: that an offenders operational base and possible future offences are revealed by the geographical location of their previous crimes
• inferences about the offender based on location (GP)

  • crime mapping = the locations of crime scenes are used to infer the likely home or operational base of an offender
  • serial offenders restrict their 'work' to areas they are familiar with (spatial consistency)
  • location can also be used alongside psychological theory to create hypotheses about the offender and their modus operandi (habitual way of working)
• types of offender (GP)

  • Canter and Larkin proposed 2 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
• circle theory (GP)

  • Canter and Larkin also suggest that the pattern of offending locations is likely to form a circle around the offender's usual residence - 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 = evidence supporting IP

  • Canter and Heritage conducted an analysis of 66 sexual assault cases using smallest space analysis - several behaviours were identified in most cases (eg, using impersonal language)
  • each individual displayed a pattern of such behaviours, helps establish whether 2 or more offences were committed by the same person ('case linkage')
  • => supports one the basic principles of IP and bottom-up approach that people are consistent in their behaviour
• counterpoint to supporting evidence for IP

  • database only made up of solved crimes which are likely to be those that were straightforward to link (circular argument)
  • IP may tell us little about crimes that have few links between them and therefore remain unsolved
• strength = evidence support for GP

  • Lundrigan and Canter collated information from 120 murder cases in the US smallest space analysis revealed spatial consistency - a centre of gravity
  • offenders leave home in different directions when dumping a body but created a circular effect (especially in the case of marauders)
  • supports view that geographical information can be used to identify an offender
• limitation = GP not sufficient on its own

  • recording of crime is not always accurate, can vary between police forces and an estimated 75% of crimes are not even reported to the police
  • even if the crime data is correct, other factors matter, eg, timing of the offence and age and experience of the offender
  • => geographical information alone may not always lead to successful capture of offender
• extra evaluation

  • Copson surveyed 48 police departments and found that advice provided by a profiler was 'useful' in 83% of cases (approach is valid)
  • BUT the same study revealed that only 3% of cases led to accurate identification
  • ALSO Kocsis found chemistry students produced more accurate profiles than detectives
  • => offender profiling may actually have little practical value when it comes to solving cases
• strength = railway rapist

  • John Duffy carried out 24 sexual attacks and 3 murders on women near railway stations in North London
  • Canter analysed geographical information from the crime scenes and combined this with details of similar attacks in the past supplied by police
  • Canter was then able to draw up an extremely accurate profile of Duffer that led to his eventual arrest and conviction