Outline the bottom up approach to offender profiling
Systematic analysis of evidence at a crime scene to reveal criminals characteristics, routine and social background
- data driven, uses investigative psychology and geographical profiling
Describe how investigative psychology helps to identify an offender
- Uses a combination of statistical analysis and psychological theory
- Info from the crime is added to a crime database
- Statistical analysis is used to search for similarities, patterns and linking crimes to predict future crimes
Describe the main techniques used in investigative psychology
• Interpersonal coherence = looking for correlation between how people behave at crime/interact with victim and what this reveals
• Time & place = can signify info about where criminal works/lives
• Forensic awareness = does evidence suggest the individual has previously committed a crime
Outline how geographical profiling helps in identifying an offender
- Uses info about location of linked crime scenes to make inferences about the likely base of the offender (combined with IP)
- also creates hypothesis about offenders thinking and modus operandi (signature)
Describe main techniques used in geographical profiling
• Spatial consistency = offenders are likely to stick in one area
• Circle theory = the pattern of offending is likely to form a circle around their usual residence (middle = centre of gravity)
• Jeopardy surface = using this info can make predictions on where they are likely to strike next
Describe the two models used in geographic profiling
** Marauder model**
= commits crimes within a criminal range from their own home
Commuter model
= travels from their home to a familiar area then commits crimes within a criminal range of that area
-Spatial decision making may reveal important info
Give a positive to the bottom up approach
More widely applicable
~ can be used for rape, murder, burglary and theft whilst top down can only be used for more extreme crimes (rape/murder)
~ not limited in application so it can help us identify more offenders
Give limitations of the bottom-up approach
Not always accurate
- can help us narrow down a list of suspects but cannot always deliver actual suspect
- vague characteristics can apply to multiple people, fitting the profile ≠ perpetrator
Countering research
- investigated 48 police forces, found to be useful in 85% of cases but only found the offender in 3%
- unreliable alone, must be used in conjunction with other techniques
Leads to wrongful conviction
- Rachel Nickell murder —> Colin Stagg was falsely imprisoned bc he met the profile’s criteria, real offender dismissed for being ‘too tall’
- should be used with caution to arrow down suspect lists
Information insufficient
- heavily relies on data provided by police
- recordings of crime/EWT aren’t always accurate + 75% of crimes go unreported
- questions how useful this approach is alone to generate an offender profile
Outline the top-down approach
Primarily focuses on investigating homicide and serial rape cases; involves creating typologies (templates) of either a disorganised or organised offender
How was data for the top down approach gathered?
FBI conducted in-depth interviews with 36 sexually motivated serial killers
Give traits of an organised offender
Pre-planned, victims reflect a ‘type’,high level of control, detached, leave little evidence, above average IQ, skilled proffesion, sexually competent, married
Give traits of a disorganised offender
Little evidence of planning, spontaneous act, impulsive nature of crime scene, lower than average IQ, unskilled work/unemployed, previous failed relationships, live alone + locally to attacks
Describe the stages of constructing an FBI profile
1 Data assimilation —> FBI review evidence from the crime scene
2 Crime scene classification —> disorganised or organised
3 Crime reconstruction —> hypothesis is created relating to the sequence of events and behaviour of victim
4 Profile generation —> hypothesis related to likely offender (e.g. demographics, physicality, behaviour)
Don’t Commit Crimes Please
Give a strength of the top-down approach
Research support —> David Canter et al conducted analysis of 100 US murders committed by different serial killers; assessed the co occurrence of different aspects of serial killing
= found a distinct subset of features across all cases which matched with the FBI’s typologies
Give limitations of the top down approach
Limited sample size of only 36, also mostly male serial killers; can’t generalise these findings onto the wider population —> lacks population validity; also beta bias so may tell us little about offending habits of women
Methodological flaws —> use of self report techniques means participants could have lied or been subject to SDB (may not want to admit to certain aspects or overexxaggerate for noteriety)
Limited application —> only applicable to more extreme crimes like murder/rape compared to bottom up approach; may therefore be less useful approach as it may lead to a lower identification of offenders overall
Oversimplification —> may not fit into only one typology, people may show signs of both (I.e. Ted bundy was planned + intelligent but sometimes impulsive + left bodies exposed), doesn’t capture complexity of criminal behaviour so may be less useful than the bottom up approach
