Bottom-up

• A strength is evidence supports investigative psychology

  Canter and Heritage (1990) did a content analysis of 66 sexual assault cases using smallest space analysis. Several characteristics were commonly identified in most cases (e.g. use of impersonal language, lack of reaction to the victim).

  This can lead to an understanding of how offender's behaviour may change over a series of offences, or establishing whether two or more offences were committed by the same person.

  This supports the usefulness of investigative psychology because it shows how statistical techniques can be applied.
• A strength is evidence supports 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 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' (close to home base)

  This supports Canter's claim that spatial information can be a key factor in determining the base of an offender.
• A strength is the approach has a scientific basis

  Canter argues that the bottom-up approach is more objective and scientific than top-down.

  Investigators can use geographical, biographical and psychological data to 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 it's use in the judicial process.
• A strength is wider application of the approach

  The bottom-up approach can be applied to a wide 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.
• A limitation is 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 (1995) surveyed 48 police forces - advice provided by a profile 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.
• What is the bottom-up approach ?


  Profilers work up from evidence collected from the crime scene to develop hypotheses about the likely characteristics, motivations and social background of the offender
• Investigative psychology = a form of bottom-up profiling that matches the details from the crime scene with statistical analysis of typical offender behaviour patterns based on psychological theory
• Geographical profiling = A form of bottom-up profiling based on the principle of spatial consistency - that an offender's operational base and possible future offences are revealed by the geographical location of their previous crimes
• 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 evidence
• Investigative psychology = Statistical analysis of crime scene 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 potentially important details about the offender, their personal history, family background etc.
• Investigative psychology = Analysis based on psychological concepts: interpersonal coherence


  A central concept to investigative psychology is interpersonal coherence - the way an offender 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 related to women for example more generally
• Forensic awareness = describes those individuals who have been subject of police interrogation before, their behaviour may denote how mindful they are of 'covering their tracks'
• Geographical profiling = Inferences about the offender based on location


  The locations of crime scenes are used to infer the likely home or operational base of an offender - known as crime mapping. Location can be used alongside psychological theory to create hypotheses about the offender and their modus operandi (habitual way of working)
• Geographical profiling = marauder and commuter types

  
  

  The assumption is that serial offenders restrict their 'work' to areas they are familiar with. Canter and Larkin (1993) proposed to models of offender behaviour:

  1. The marauder - operates close to their home base
  2. The commuter - likely to have travelled a distance away from their usual residence when committing a crime
• Geographical profiling = circle theory uses offending locations 


  Canter and Larkin suggest that the pattern of offending locations is likely to form a circle around the offenders 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).