Offender Spatial Decision-Making
Total Page：16
File Type：pdf, Size：1020Kb
6: The spatial mobility of offenders (part 1) – principles and concepts Dr Spencer Chainey The Jill Dando Institute of Security and Crime Science, University College London @SpencerChainey Outline and learning objectives • The key principles and concepts that underpin offender mobility and offender spatial decision-making behavior – Classifying types of location that are of interest when examining the spatial mobility of an offender – The journey to crime and offender search behavior – Offender ‘hunting’ methods – Target backcloth • Principles and concepts determine characteristics about the offender's spatial behaviour that could be used to assist their investigation and apprehension, predict behaviour and mitigate threats • Example/discussion: a series of sexual assaults in South London Consider the following scenario 1. Following a long running dispute with one of your neighbours, and a heated argument after a loud party they had the night before you decide to set fire to his/her car. – Where and when would you do it? – Why would you choose that location? Consider the following scenario 2. You are a sex offender and desire a victim aged 18 to 25 years of age – Where would you go to find a suitable victim? – How would you get there? – Why would you choose that location? Offender mobility and offender spatial decision-making behavior The theory so far … • Crime pattern theory: a model to explain why an offender chooses a particular location to commit a crime – Awareness of the area, availability and familiarity of crime opportunities, previous experience of crime commission • Activities that take place in places are not static – Social, economic and institutional structures operate in these places – Change over time in opportunity structure – Influences when offenders commit crime • Motivations are bounded by a degree of rationality in decision-making – Preference to commit offences in areas where they are comfortable, where risks are lower, to minimize effort • The combination of RAT, RCP and CPT help us to consider space in terms of a criminal geographic landscape Offence 1 – Electric Avenue, Brixton, London • Saturday, 17th April 1999 (nail bomb) Offence 2 – Brick Lane, Shoreditch, London • Saturday, 24th April 1999 (nail bomb) • What would lead you to think the bombings were committed by the same person? Offence 3 – Admiral Duncan Pub, Soho, London • Friday evening, 30th April 1999 (nail bomb) • Same person? Why these locations? The London Nail Bomber – David Copeland Offender mobility and offender spatial decision-making behavior In this module … • Why an offender choses a particular location • Why choses a particular person (or target) Investigation: the location acts as clue, because it tells us something about the offender (mobility and spatial decision-making behavior) Mitigating threats: we can predict offender mobility and offender spatial decision-making behavior, and identify vulnerable/high risk targets Incident location types • Each piece of location information can act as a clue • The more locations, the more information about mobility and spatial decision-making behavior Example: murder Crime locations combinations – murder Encounter Site E A M D 1 Attack Location Murder Site E A M → D Deposition Site E A → M D E → A M D 2 E A → M → D E → A M → D E → A → M D 3 E → A → M → D 4 Other relevant ‘crime’ location types • Property deposition (clothing/weapon/stolen articles) • Vehicle deposition (victim/offender) • Mobile phone use • Landline phone calls (police/media/family) • Social media activity • Letters sent • Credit card usage • CCTV • Automatic number plate recognition Amelie’s home 9:39 Route of 267 bus 9:59 – last sighting Amelie Delagrange Route walked 21 August 2004 Amelie’s home 9:39 Amelie attacked and murdered Route of 267 bus 9:59 – last sighting Amelie Delagrange Route walked 21 August 2004 ‘Bus stop stalker’ series Attack: Kate Sheedy, May 18 2004 Attack: Anne Marie Rennie, Oct 15 2001 Amelie Delagrange, Marsha McDonnell, Feb 3 2003 21 Aug 2004 Description of attacker as strong, stout man Amelie Delagrange Anne Marie Rennie Marsha McDonnell Kate Sheedy 2001 2002 2003 2004 2005 Amelie’s phone: 20 mins after assault ‘unexpected Kate Sheedy disconnection’, consistent with phone disposal in water Potential property disposal sites Anne Marie Rennie Amelie murder location • crossing points of Thames • reservoirs Marsha McDonnell ‘Bus stop stalker’ series Attack: Kate Sheedy Attack: Anne Marie Rennie Marsha McDonnell Amelie Delagrange Amelie Delagrange Anne Marie Rennie Marsha McDonnell Kate Sheedy Amelie’s phone 2001 2002 2003 2004 2005 ‘Bus stop stalker’ series Attack: Kate Sheedy Attack: Anne Marie Rennie Marsha McDonnell Levi Bellfield Amelie Delagrange Milly Dowler Amelie Delagrange Milly Dowler Anne Marie Rennie Marsha McDonnell Kate Sheedy 2001 2002 2003 2004 2005 Milly disappears here White van (matching description of vehicle sighting connected to Amelie’s murder) purchased at BCA Girlfriend’s car Bellfield took daughter horse riding at Yateley Heath - loaned van to friend Last sighting of Milly Offender hunting methods: search and attack • Consideration of the offender's hunting behaviour can help in the interpretation of their spatial behaviour Offender hunting methods: search and attack • The journey to crime: simple but useful concept • The search to crime: is longer, may require patience • Potential for the offender to be identified from their suspicious activity, or from targeted surveillance in the area when the offender is most likely searching for his (or her) targets Offender hunting methods/typoloogies •Search for suitable victim/target –Hunter, commuter, troller, trapper •Method of attack –Raptor, stalker, ambusher Offender hunting methods/typologies: search Search - hunter • Offender who sets out specifically to search for a target • Search is often from offender’s home • Search through areas in their awareness space that they believe contain suitable targets • Criminal activity is generally confined to the offender’s area of residence Offender hunting methods/typologies: search Search - commuter • Offender who sets out specifically to search for a target, but where target availability is greater away from home • Search is based from a location other than the offender’s residence • Involves the offender travelling to an area where the search process commences Offender hunting methods/typologies: search Search - Troller • Offender who, while involved in other non-criminal activities, opportunistically encounters a victim (or target) – ‘Other non-criminal activities’: the offender's normal routine activities at the time of the encounter e.g., driving home and spotting an opportunity to commit crime • Troller crimes are often spontaneous Offender hunting methods/typologies: search Search – Trapper • Offender who has an occupation where potential victims come to him or her • Or uses subterfuge to entice victims into the offender's home or some other location for which the offender has some control over The London Nail Bomber – David Copeland Hunter Commuter Troller Was Copeland and Trapper hunter, commuter, trapper or troller? Offender hunting methods/typologies: attack Attack methods • Raptor: offender attacks on encounter • Stalker: the offender follows a victim, and then attacks them – Typically involves the offending moving in to the victim’s activity space, and waiting for an opportune moment to strike – This means the offender may commit the crime away from their own awareness space • Ambusher: attacks a victim who has been enticed to a location ‘Bus stop stalker’ series Attack: Kate Sheedy Attack: Anne Marie Rennie Marsha McDonnell Levi Bellfield Amelie Delagrange Search: Hunter, commuter, troller, trapper? Attack: Raptor, stalker, ambusher? Milly Dowler Amelie Delagrange Milly Dowler Anne Marie Rennie Marsha McDonnell Kate Sheedy 2001 2002 2003 2004 2005 Offender hunting methods/typologies • For each of the search methods and the different styles of attack that then follow, different spatial patterns can result – From which different interpretations of the geographic anchor of the offender are required • No simple statistical test to determine hunting method/typology • Requires a careful interpretation of incidents, and experience working cases Target backcloth • Relates to areas of opportunity – The availability of targets varies across space • Target backcloth is the temporal and geographic distribution of ‘suitable’ targets • Consider the target backcloth issues for the offender who targets one or more of the following fixed targets to commit a robbery – Banks – Convenience stores – How may this impact on the geographic distribution of offences and the strategies/tactics that may be used to catch this offender? Target backcloth • Consider the target backcloth issues for the offender who is victim specific, e.g., he targets one of the following category of victim – Prostitutes – Children – Elderly • How may this impact on the geographic distribution of offences and the strategies/tactics that may be used to catch this offender? Target distribution and availability • Distribution and availability of targets can indicate how often the offender is hunting • Targets that occur infrequently in the environment force the offender to a specific location – The rarer a target opportunity, the further the offender has to travel, or the more often he has to hunt • ‘Patchy’ target distributions distort the spatial pattern of crimes – The crime sites are less a function of the offender’s