Offender profiling

• The top down approach is an American approach that begins with looking at crime scenes and drawing conclusions about the offender, this can build a profile of the offender.
• The top down approach also involved interviewing criminals and seeing if their behaviours mimic the crime scene.
• The top down criminal can either be disorganised or organised, this was proposed by Hazelwood and Douglas.
• There was a later 3rd top down classification called mixed.
• Canter et al tested the accuracy of the disorganised and organised offender types. He carried out a content analysis on 100 serial killers in the US. He found a higher number of disorganised crimes, and that types weren't explicit to distinguish. This deems the approach's criteria inadequate and subjective.
• Jackson and Bekerian devised 4 stages of the top down approach in action. 1. Data assimilation, 2. Crime classification (org or disorg), 3. crime construction 4. Profile generation
• Stage 3 is crime construction, which involves the creation of the crime scene to find out motives and predictions of profile.
• A limitation of the top down approach is that is focusses on aggressive and violent crimes, with most of the offenders being male. This deems t the approach beta bias and lacking in generalisability.
• Females in the top down approach may express different behaviours and crime characteristics that males.
• The bottom up approach is a British invention, developed by Canter. Canter made it due to his belief that the top down was based on a hunch and wanted his approach to be based on facts.
• Egger made key assumptions about the bottom up approach. Interpersonal coherence (consistency between offending and everyday behaviour. Time and place (comminate something about their place of work or home). Criminal career (committed in a similar fashion to other crimes, provide indication on how their crimes may develop). Criminal characteristics. Forensic awareness (understanding of police investigations, and previous encounters with the police)
• Geographic profiling is a form of bottom up and takes note of Egger's time and place assumption. Rossmo refers to offenders behaviour as hunting patterns, and through examining locations and their relationships it can tell where the offender lives or works.
• A case study for geographical profiling is John Duffy or the "railway rapist"
• John Duffy expressed many of eggers assumptions. He was abusive to his ex wife (interpersonal coherence). He had a criminal record and made a effort to clear evidence (forensic awareness). He lived and worked on railways as a carpenter (Time and place).
• Geographical profiling assumptions

  Locatedness (Meet, attack, dispose, several locations identified). Centrality ( correlation to where the offender lives or works). Sytematic location choice (familiarity). Comparative case analysis.
• Within the centrality principle of geographical profiling, canter identified marauders and commuters. He also developed the circle theory, that crimes occurred in a cluster around a central point of familiarity (workplace or home).
• Bottom up approach focusses on the relationship between victims and offenders as well as it being based on past data.
• A benefit of the bottom up approach is that it can be applied to more than aggressive and violent crimes, like arson and B&Es.
• A limitation of the bottom up approach is that John Duffy is a case study. John is a male, having unique a circumstance of the crime (London) and a rape and murder case. This deems the case study to be unrepresentative of the general population and beta bias.
• However, a positive of the bottom up approach is that John Duffy was charged and received a life sentence. He was convicted of 3 murders and 7 rapes, all thanks to the approach.
• A limitation of the bottom up approach is that even though Canter claimed that his approach was based off of facts, he first believed that John Duffy did martial arts due to his physicality which was not a objective estimation.