EVERY DAY, EACH ONE OF US MAKES GEOGRAPHIC DECISIONS. The way we choose where to shop, which way to drive to work and where to walk our dogs all relate in a predictable way to where we live - usually the shortest routes and the closest locations. The patterns in which normal people move are now being used to predict how repeat criminals behave.

This geographic profile of two robbers (white dots show each robbery, superimposed on a map of Vancouver) was made public by Crime Stoppers. The robberies stopped immediately afterward. The black dot indicates the probable neighbourhood in which the robbers were living at the time of the spree. (Courtesy of Environmental Criminology Research Inc.)

Vancouver Police Detective Inspector Kim Rossmo, the first working police officer in Canada with a doctorate in criminology, has developed a technique known as 'geographic profiling' to nab serial killers, rapists and thieves. It is based on the emerging discipline of environmental criminology which focuses on the geography of a criminal act rather than the motivation. Geographic profiling involves superimposing crime sites on a grid of any given city. Taking into account the typical journey distance to crime sites, a computer repeatedly estimates the distance between a crime site and a given grid point, then calculates the probability that a given grid point represents an offender's home base. The process is repeated for evey grid point and every crime site until a 3-D graph is produced, showing the offender's most likely area of residence.

Rossmo's technique, which he developed during graduate studies at Simon Fraser University in B.C., has gained him worldwide attention from organizations like Scotland Yard, the FBI's Behavioural Science Unit, and the Dutch police, and has been used to hone in on a number of suspects in the Vancouver area, as well as high-profile cases like that of Paul Bernardo in Ontario.

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(This information came from an original article by Taras Grescoe that appeared in Canadian Geographic magazine, Sept/Oct 1996. It may not be reproduced without written permission from Canadian Geographic.)