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Study on Geo-Behavioural Profiling Systems by Prof. David Canter & Laura Hammond, University of Liverpool, UK. Analyzing 92 offence series in London borough over 4 years. Utilizing various prioritization strategies and models, including concepts like Criminal Range Decay Functions and Offence Map development. Comparison of 15 models for improved crime pattern examination. Examples from burglaries in Wandsworth showcasing offenders with different crime distributions.
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Testing the Effectiveness of Geo-Behavioural Profiling Systems Professor David Canter & Laura Hammond Director, Centre for Investigative Psychology The University of Liverpool,UK www.i-psy.com
Study of effectiveness of various prioritisation strategies 92 offence series in a London borough. All identified series over four years/
Various Models Illustrated from the crimes of Jack the Ripper
The ‘canonical’ map Chapman 8.9 – 6.00 Nichols 31.8 –3.40 Kelly 9.11- 7.00? Stride 30.9 – 1.00 Eddowes 30.9 – 1.45
Two further concepts Criminal Range Decay Functions
The Distance Decay Function, An example from serial arsonists 35 30 25 20 15 10 5 0 0-0.1 0.51-0.99 1.51-2.00 2.51-3 4.01-5 6.01-7 10+ 0.11-0.5 1.00-1.5 2.01-2.5 3.01-4 5.01-6 7.01-8 Range of Distances traveled by Arsonists
Offence Map: Developing the Search Tool that incorporates various distance functions. 1st Crime 2nd 4th 3rd 5th
The system assigns a priority to each known offender using various criteria. Prioritised search area
Cumulative Percentages of the Rank Achieved by Actual Offender in Dragnet Prioritization for different criteria. • Criteria • Distance from centre of circle defined by 2 furthest crimes • Distance from centre of gravity (centroid) • Optimum negative log decay function • Negative log decay function with buffer 50% of actual offenders are in the top 5 prioritized just by geographical location. iOPS allows this to be improved by also using M.O. matching.
(N = 92) COMPARISON OF 15 DIFFERENT MODELS
Need for more context specific examination of crime patterns Taking account of • Land use • Opportunities for crime • Guardianship • Targeting • Transport routes • Temporal sequences
Offender 34 crimes 1 home location Offender 1: 34 CRIMES 1 HOME LOCATION
Offender 34 crimes 1 home location Offender 2: 34 CRIMES 1 HOME LOCATION
2 Offenders with different distributions of crimse in relation to Southside Centre in Wandsworth Southside Centre Offender 34 crimes 1 home location Offender 34 crimes 1 home location
EXAMPLES FROM BURLGARIES IN WANDSWORTH PNC data 12 offenders All crime types 1992-present Offender 1: 10 CRIMES 2 HOME LOCATIONS
Offender 8: 24 CRIMES 1 HOME LOCATION
Offender 3: 20 CRIMES 3 HOME LOCATIONS
Offender 2: 21 CRIMES 3 HOME LOCATIONS
Offender 7: 13 CRIMES 2 HOME LOCATIONS
Offender 5: 19 CRIMES 3 HOME LOCATIONS
Offender 11: 48 CRIMES 3 HOME LOCATIONS
Offender 12: 53 CRIMES 2 HOME LOCATIONS