Bottom up approach

• What is it ?

  Make inferences about criminals based on evidence from the crime scene, not previous crimes

  • no initial assumptions are made
  • profile is built from data
  • cognitive social approach
  • data driven

  statistical techniques are used to produce predictions about the likely characteristics of the offender
• What are the two processes involved in bottom up ?

  1. Geographical profiling
  2. investigative psychology
• What is geographical profiling ?

  people reveal themself through the locations they choose and timings

  • where rather than who
  • analyse locations of a connected series of crimes, spatial relationships and how they relate to the criminals house and where they will commit next
• What are the two geographical profiling techniques ?

  1. Circle theory
  2. criminal geographical targeting
• Circle theory ?


  Canter

  • spatial consistency + distribution of crimes

  - enables to asses whether they are a commuter or a Marauder

  • offenders house in the middle
• Criminal geographical targeting ?

  rossmo

  • based on spatial consistency
  • their operational base and furure offences are linked
  • known offences put into a programme to generate a heat map
  • in the middle is the house
  • related to time distance and movement to or from crime scenes
• What is investigative psychology ?

  Canter

  • profiling should be based on psychological theory

  1. interpersonal coherance
  2. forensic awareness
  3. smallest space analysis
• What is interpersonal coherence ?

  • people are consistent in their behaviour and will be links with elements of the crime and how they behave in daily life
  • people’s behaviour can also change over time
• Forensic awareness ?

  • certain behaviours can reveal awareness of police techniques and past experience
  • e.g rapists conceal fingerprints as have been a. Burglar
• Smallest space analysis ?

  A statistical technique that correlates offender characteristics + crime scenes

  • canter analyses 47 crime scenes and offender characteristics from 82 murder cases where the victim was a stranger and found 3 underlying themes

  1. instrumental opportunist
  2. instrumental cognitive
  3. expressive impulsive
• instrumental opportunist ?


  Using murder to obtain something/goal

  • took the easiest opportunity
• Instrumental cognitive ?


  particular concern about being detected thus more planned
• Expressive impulsive ?

  • uncontrolled
  • in the heat of strong emotions
  • may feel provoked by the victim
• Evaluation of bottom up ?

  1. research support - circle theory
  2. research support- police
  3. based on data
• Research support - circle theory ?

  Support circle theory by distinguishing between Marauders and commuters in 46 sexual assult

  - 91% were marauders

  if all are marauders then the classification isn’t useful

  - PETHERIK pointed out if their home isn’t in the middle police will look at the wrong place
• Copson (1995)

  • surveyed 48 uk police forces + found 83% said useful but only let to an accurate identification in 3%
• Based on data ?

  Relies on statistical analysis + use of data bases

  • scientific + objective