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Testing the Effectiveness of Geo-Behavioural Profiling Systems

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

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Testing the Effectiveness of Geo-Behavioural Profiling Systems

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  1. 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

  2. Study of effectiveness of various prioritisation strategies 92 offence series in a London borough. All identified series over four years/

  3. Various Models Illustrated from the crimes of Jack the Ripper

  4. 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

  5. The ‘canonical’ map

  6. Circle Hypothesis Calculation to Locate Ripper’s Base

  7. Central Circle in Whitechapel

  8. Centre of Gravity of Murder Locations

  9. Two further concepts Criminal Range Decay Functions

  10. Criminal ‘range’

  11. 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

  12. Optimal Function of Distance from Offence to ‘Home’

  13. Offence Map: Developing the Search Tool that incorporates various distance functions. 1st Crime 2nd 4th 3rd 5th

  14. The system assigns a priority to each known offender using various criteria. Prioritised search area

  15. 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.

  16. (N = 92) COMPARISON OF 15 DIFFERENT MODELS

  17. Need for more context specific examination of crime patterns Taking account of • Land use • Opportunities for crime • Guardianship • Targeting • Transport routes • Temporal sequences

  18. Offender 34 crimes 1 home location Offender 1: 34 CRIMES 1 HOME LOCATION

  19. Offender 34 crimes 1 home location Offender 2: 34 CRIMES 1 HOME LOCATION

  20. 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

  21. EXAMPLES FROM BURLGARIES IN WANDSWORTH PNC data 12 offenders All crime types 1992-present Offender 1: 10 CRIMES 2 HOME LOCATIONS

  22. Offender 8: 24 CRIMES 1 HOME LOCATION

  23. Offender 3: 20 CRIMES 3 HOME LOCATIONS

  24. Offender 2: 21 CRIMES 3 HOME LOCATIONS

  25. Offender 7: 13 CRIMES 2 HOME LOCATIONS

  26. Offender 5: 19 CRIMES 3 HOME LOCATIONS

  27. Offender 11: 48 CRIMES 3 HOME LOCATIONS

  28. Offender 12: 53 CRIMES 2 HOME LOCATIONS

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