Bottom-up approach to offender profiling

• Bottom-up approach


  Profilers work from the evidence collected from the crime scene to develop hypotheses about the likely characteristics, motivations and social background of the offender.
• How are the top-down and bottom-up approach different?

  • The British bottom-up model does not begin with fixed typologies
• Investigative psychology

  Attempts to apply statistical procedures, alongside psychological theory to the analysis of crime scene evidence.
• What is the aim of investigative psychology

  • To establish patterns of behaviour that are likely to occur or coexist across crime scenes.
  • To develop a statistical database which then acts as a baseline for comparison.
• What advantages are there to creating a statistical database?

  • The database may reveal specific details of an offence, related offences, history, family background.
  • This helps to reveal whether a series of offences are linked in that they are committed by the same person.
• What are the 3 components of investigative psychology?

  • Interpersonal coherence
  • Time and place
  • Forensic awareness
• Interpersonal coherence (component of investigative psychology)

  • Refers to the way an offender behaves at the scene.
  • E.g how they interact with the victim may reflect their behaviour in more everyday situations.
  • For example, whilst some rapists want to maintain maximum control and humiliate their victims some are more apologetic.
  • This may tell the police something about how the offender relates to women more generally.
• Time and place (component of investigative psychology)

  • Time and place are key variables as they may indicate where the offender lives.
• Forensic awareness (component of investigative psychology)

  • Offenders may have been investigated by the police before and may know how the police work.
  • This means they may try to cover their tracks after offending which may mean they already have a criminal record or have done something similar before.
  • E.g rapists who conceal fingerprints because they have previous convictions for burglary.
• Geographical profiling

  • Uses information about the location of linked crime scenes to make inferences about the likely home or operational base of an offender.
  • Known as crime mapping on the principle of spatial consistency (people commit crimes within a limited geographical space).
  • Can be used in conjunction with psychological theory e.g investigative psychology to create hypotheses about how the offender is thinking.
• What is the assumption of geographical profiling?

  • That serial offenders will restrict their work to geographical areas they are familiar with, so understanding the spatial pattern of their behaviour provides investigators with a centre of gravity- which is likely to include the offenders base.
• What is the theory which matches the idea that offending patterns form a circle around the offenders home base?

  • Canter’s circle theory (Canter and Larkin)
• How does the distribution of offences help describe the offender?

  • The marauder: who operates near their home base
  • The commuter: Who is likely to have travelled a distance away from their usual residence.
• How does the spatial decision-making of the offender help the investigative team?

  • Offers important insight into the nature of the offence I.e whether it was planned or opportunistic.
  • Reveals factors about the offender e.g mental maps, mode of transport, employment status, approximate age.
• How did David Canter come into dominance?

  • Assisted the police in the capture of John Duffy
  • 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 similar attacks in the past supplied by police.
  • Canter drew a profile of Duffy which was accurate and led to his arrest.
• Evidence supporting investigative psychology

  • Canter and Heritage conducted an analysis of 66 sexual assault cases. The data was examined using smallest space analysis. Several behaviours were identified as common in different samples of behaviour such as impersonal language and lack of reaction to victim.
  • Each individuals displayed a characteristic pattern on such behaviours and this can help to establish whether 2 or more offences were committed by the same person.
  • Supports investigative psychology that people are consistent in their behaviour.
• Evidence for geographical profiling

  • Lundrigan and canter collected information from 120 murder cases involving serial killers in the US. Smallest space analysis was used, and revealed spatial consistency in the behaviour of killers.
  • The place where the body was disposed of was in a different direction to the last, creating a centre of gravity. The offenders base was always in the centre. This was especially true of those who committed crime close to home (marauders).
  • Geographical profiling and spatial information is key in determining the base of an offender.
• Why may geographical profiling be insufficient on its own?

  • Success of geographical profiling is reliant on the quality of data that the police and provide. The recording of the crime can vary between police forces and an estimated 75% of crimes are not even reported to the police.
  • Even if information is correct, critics claim that other factors are important in creating a profile e.g timing of the offence, age and experience of offender.
  • Therefore this suggests that geographical information may not always lead to a successful capture of the offender.
• Why has the bottom-up approach led to mixed results?

  • Copson surveyed 48 police forces and found that advice provided by the profiler judged to be useful in 83% of cases, but only in 3% of case led to identification of offender.
  • The Rachel Nickell case offers a stark reminder of when and how profiling can be misused. Nickell’s real killer Robert Napier was ruled out of the police enquiry by junior officers who judged him to be too tall to fit the police profile they had been given.
  • Suggesting it may have little practical value.
• Outline the bottom-up approach to offender profiling?

  • Data driven approach that involves using data from crime scene and the victim to build a statistical database.
  • Statistical information is analysed to find relationships between crimes.
  • investigative psychology (David Canter), assumptions include, interpersonal coherence (offender behaves consistently at the crime scene and in real life), details of time/place, and forensic awareness.
  • Geographical profiling: using crime-scene location and local knowledge to provide clues to offenders life, job, habits (centre of gravity hypothesis)