Kim Rossmo worked as a beat cop in Vancouver, British Columbia, for 20 years. His work on geographic profiling led to a rapid rise through the ranks, which he says caused some resentment among his colleagues. He eventually left Vancouver to concentrate fully on his new discipline. Now research director of the American Police Foundation in Washington, DC, he has used geographic profiling in more than 150 criminal investigations.

How does geographic profiling work?

Crimes are not just random - there's a pattern. It has been said criminals are not so different from shoppers or even from lions hunting their prey. When an offender has committed a number of crimes, they leave behind a fingerprint of their mental map, and you can decode certain things from that. We put every crime location into a computer program and it produces a map showing the most probable areas the police should target. ...