Geographic Profiling

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Geographic Profiling

• Gareth Norris
• 15th March, 2005

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Some Important Principles for Understanding
Geographic Behaviour

• Shaw and Mckay (1942)
• The Chicago School
• Zipf (1950) Least Effort Principle
• Brantingham Brantingham (1982) Environmental
  Psychology

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Brantingham Brantingham (1982)

• Spatial knowledge of an area is gained through
  everyday activities.
• Peoples spatial behaviour is also governed by
  familiarity and effort.
• Criminal behaviour is therefore expected to
  mirror non-offending spatial behaviour.
• The places frequented when not offending will
  have a bearing on areas used to offend.

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Pub
Work
Home
Friends
Shopping
Mental Map
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Peter Sutcliffe The Yorkshire Ripper

• Attacked 21 women in the North of England
• Mostly prostitutes
• Sutcliffe was a lorry driver
• Enquiry lasted for over five years and generated
  enormous amounts of information
• Had been questioned by the police on a number of
  occasions

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Stuart Kind Centre of Gravity.
Take a map of the area in which the 17 Yorkshire
Ripper offences occurred and mark each location
with a pin. Next take an 18th pin and join it to
each of the 17 locations by a piece of thread.
That location of the 18th pin which minimizes the
amount of thread required is the centre of the 17
offences.
Kind, S.S. (1987). Navigational ideas and the
Yorkshire Ripper Inquiry. Journal of Navigation,
40(3), 385-393. http//www.forensic.demon.co.uk/d-
load.html
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H
H
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David Canter the circle theory

• identifying the two crime locations
  furthest apart from each other. Using these
  locations as the diameter, a circle can be drawn
  that includes all the offences. The hypothesis is
  that the criminal will be found to live inside
  that circle, possibly close to the middle of it.

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Circle Theory
Criminal Range
Home Range
H
H
Marauder
Commuter
Canter, D. Larkin, P. (1993). The
environmental range of serial rapists. Journal
of Environmental Psychology, 13, pp. 63-69.
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Accuracy

• Godwin Canter (1997) 85 of US Serial Killers
  live within circle
• Canter Larkin (1993) 87 of UK Serial Rapists
• Kocsis Irwin (1997) 71 Australian Serial
  Rapist 82 Serial Arsonists
• Kocsis, Cooksey, Irwin, Allen (2002) 50 of
  Australian Serial Rural Burglars

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Computerized Crime Mapping

• Attempts to emulate theory and predict offender
  residence
• Rossmo CGT
• MapInfo, Predator, Rigel etc.
• Canter Dragnet

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Criminal Geographical Targeting (CGT)

• By inverting research that has focused on
  relating crime places to offender residences, the
  locations of a series of crimes can be used to
  determine where an offender might reside. Dr Kim
  Rossmo.

Rossmo, K.D. (2000). Geographic Profiling. CRC
Press.
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Hunting Typologies

• Search Hunter, Poacher, Troller, Trapper
• Attack Raptor, Stalker, Ambusher
• Target Backcloth - opportunity
• Hunting Style affects spatial distribution

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Jeopardy Surface

• Developed whilst working for Royal Canadian
  Mounted Police
• Three years experience investigating
  interpersonal crimes
• Superior level of investigative skill

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Insertion of crime locations into Dragnet.
Run analysis to produce prioritization map.
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Prioritization diagram can be transposed onto
street map to determine locations of interest.
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Computers vs. People

• 21 Students in each group (control
  experimental)
• Ten crime series five locations for each
• Experimental group given two heuristics
• - majority of offenders homes within circle
  defined by two furthest offences
• - majority of offenders commit offences close to
  home

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Effect of training on prediction of home
location
Snook, B., Canter, D. Bennell, C. (2002).
Predicting the Home Location of Serial
Offenders A Preliminary Comparison of the
Accuracy of Human Judges with a Geographic
Profiling System. Behavioural Sciences and the
Law, 20, pp. 109-118.
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Implications

• Indicates that principles involved are effective
  (distance decay circle theory)
• Uniform improvement not due to intuition or
  gut feeling
• May be other principles that need to be
  identified, i.e. commuters
• Casts doubt on utility of computerized systems
  and specialized training

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Future Directions Incorporating Temporal
Information

• Godwin Canter (1997) Dump sites tend to be
  at a further distance than points of first
  encounter
• Canter Heritage (1994) Rapists who offend
  outdoors travel further than those who attack
  indoors
• Davies Dale (1995) Older offenders travel
  further
• Pettiway (1982) White offenders travel further
  than black
• Le Beau (1993) Industrial vs. Residential
  areas
• Rhodes and Conly (1981) Crime type

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Problems and Limitations

• Doesnt give an address provides areas of
  priority
• Relies on accurate data and correct linking
• Size and demographics of area
• Not applicable to all crimes

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References

• Kind, S.S. (1987). Navigational ideas and the
  Yorkshire Ripper Inquiry. Journal of Navigation,
  40(3), 385-393.
• http//www.forensic.demon.co.uk/d-load.html
• Rossmo, K.D. (2000). Geographical Profiling.
  Florida CRC.
• Canter, D. Larkin, P. (1993). The
  environmental range of serial rapists. Journal
  of Environmental Psychology, 13, pp. 63-69.
• Brantingham, P.L. Brantingham, P.J. (1982).
  Mobility, notoriety, and crime A study of crime
  patterns in urban nodal points. Journal of
  Environmental Criminology, 11, 89-99.