The bottom-up approach to offender profiling

• 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
• Where was the bottom-up approach created?

  In Britain
• How is the bottom-up approach different to the top-down approach?

  It doesn't begin with fixed typologies - profile is data-driven and emerges as the investigator engages in deeper and more rigorous scrutiny and analysis of the details of the offense

  It is also much more grounded in psychological theory
• Investigative psychology

  Matches details from the crime scene with statistical analysis of typical offender behaviour patterns based on psychological theory - aims to establish patterns of behaviour that are likely to occur, or coexist, across crime scenes
• What is the purpose of investigative psychology?

  To develop a statistical database which acts as a baseline for comparison - specific details of an offense, or related offenses, can be matched against the database to reveal important details about the offender, their personal history, family background, and can determine whether a series of offenses are linked in that they are likely to have been committed by the same person
• 3 central concepts of investigative psychology

  Interpersonal coherence

  Significance of time and place

  Forensic awareness
• Interpersonal coherence

  The way an offender behaves at the scene, including how they interact with the victim, may reflect their behaviour in more everyday situations
• Significance of time and place

  May indicate where the offender is living
• Forensic awareness

  Describes individuals who have been the subject of police interrogation before, so their behaviour may denote how mindful they are of 'covering their tracks'
• Geographical profiling

  Uses information about the location of linked crime scenes to make inferences about the likely home or operational base of an offender - crime mapping

  Can be used in conjunction with psychological theory (like investigative psychology) to create hypotheses about how the offender is thinking and their modus operandi
• What principle is geographical profiling based on?

  Spatial consistency
• Spatial consistency

  People commit crimes within a limited geographical space - serial offenders will restrict their work to 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 offender's base (often in the middle)
• Canter's circle theory

  The pattern of offending forms a circle around the offender's home base, and the distribution of offenses can lead to 2 offender descriptions
• 2 offender descriptions according to Canter's circle theory

  Marauder and commuter
• Marauder

  Operates in close proximity to their home base
• Commuter

  Likely to have travelled a distance away from their usual residence