Forensics - Offender profiling Flashcards
top-down & bottom-up (inc. geographical)
Offender profiling
Investigative techniques to narrow down a suspect list by identifying major characteristics from the crime scene
Top-down approach
Uses general classification to make judgements about the offender based on the profiler’s intuition & experiences (used by FBI)
Organised offenders
- Planned
- Victims are targeted
- Little evidence left
- Intelligent
- Typically married w/kids
Post offence: returns to the scene, follows the investigation via news, volunteers information
Interviews: direct strategies
Disorganised offender
- Unplanned
- Spontaneous offences/victims
- Evidence & body left at crime scene
- Unskilled w/low intelligence
- Loners
Post offence: returns to the scene to relive, keep newspaper cuttings of events & a diary
Interviews: empathise with offender, indirectly introduce evidence
4 stages of constructing profile (T-D approach)
- Data assimilation (review evidence, photos, medical examiner report, victim background)
- Crime scene classification (organised or disorganised)
- Crime reconstruction (hypotheses about sequence of events & behaviour)
- Profile generation (hypotheses related to the offender i.e. physical characteristics, demographic)
Strengths of T-D profiling
+ Supporting evidence:
1. Canter et al - 100 cases by serial killers found a subset of features that matched the FBI’s typology
2. Maketa - application to burglaries found 85% rise in solved cases & added two new categories (interpersonal & opportunistic)
3. McCrary & Grant - used profiling on a man responsible for murdering prostitutes to find close match
+ Behavioural consistency (create links between offences based on crime scene similarity)
Limitations of T-D profiling
- Contrasting characteristics (Godwin - difficulty classifying as could have high IQ but leave evidence)
- Change in modus operandi (offenders become more forensically aware & organised -> hard to link their earlier offences to later ones)
- Methodological issues (Canter et al - poor sample used for creation of categories [only 36 & only sexual offenders], was not standardised)
- Gives little information about offender (Mischel - driven by the situation -> does not reflect how they are in everyday life)
Bottom-up approach
Collects details/evidence of the crime scene & statistically analyses the data to generate predictions/hypotheses (British) [Data-Driven]
Canter’s 5 factor model (B-U approach)
1! Interpersonal coherence (interactional style with victim reflects daily life)
2! Time & place significance (chosen to commit crime there so must hold some importance to offender i.e. comfortabilities & schemas)
- Criminal characteristics (how crime was committed reflects personality)
- Criminal career (following same offender sees crimes changing over experience)
- Forensic awareness (how knowledgeable the offender is of the CJS & forensics)
Assumptions of geographical profiling (B-U)
- Crimes are not random
+ Least effort principle (choose place closest to them out of all attractive locations)
+ Distance decay (number of crimes reduce further away they are to their home base until their confidence grows [buffer zone around home base - decrease recognition])
+ Circle center of gravity (circle can be drawn from furthest points out to encompass all crimes & the home base)
Commuter & Marauder theory (B-U)
A commuter style offender travels away from their home base and usual places
A marauder style offender remains closer to their home base
Strengths of B-U profiling
+ Spatial consistency (Lundrigan & Canter - location of body disposals created a circle of gravity & was noticeable in 120 marauder cases)
+ Useful (Copson - 83% of police forces judged it as helpful -> validity)
+ Applicable to wider range of crimes (uses locations -> generalisable)
+ Scientific (objective & measurable, statistical analysis & psychological theories)
Limitations of B-U profiling
- Reliant on data quality (75% crimes are not reported to police & other factors are equally as important as location i.e. timing of offence & age of offender)
- Issues with validity (Koesis et al - chemistry students more accurate at profiling than experienced professionals)
- [HOWEVER] Useful (Copson - 3% lead to accurate identifications)
