Calculating crime

New math tools could help cops find robbers

People who solve crimes look for patterns that might reveal the identity of the criminal. A mathematician from Maryland has come up with tools to help police find crooks.


When you think about math, you probably don’t think about breaking the law, solving mysteries or finding criminals. But a mathematician in Maryland does, and he has come up with mathematical tools to help police find crooks.

People who solve crimes look for patterns that might reveal the identity of the criminal. It’s long been believed, for example, that crooks will break the law closer to where they live, simply because it’s easier to get around in your own neighborhood. If police see a pattern of robberies in a certain area, they may look for a suspect who lives near the crime scenes. So, the farther away from the area a crime takes place, the less likely it is that the same criminal did it.

But Mike O’Leary, a mathematician at Towson University in Maryland, says that this kind of approach may be too simple. He says that police may get better clues to the location of an offender’s home base by combining these patterns with a city’s layout and historical crime records.

The records of past crimes contain geographical information and can reveal easy targets — that is, the kind of stores that might be less difficult to rob. Because these stores are along roads, the locations of past crimes contain information about where major streets and intersections are. O’Leary is writing a new computer program that will quickly provide this kind of information for a given city. His program also includes census, or survey, information about the people who live in the city, and information about how a criminal’s patterns change with age. (It’s been shown, for example, that the younger the criminal, the closer to home the crime.)

Other computer programmers have worked on similar software, but O’Leary’s uses more math. The mathematician plans to make his computer program available, free of charge, to police departments around the country.

The program is just one way to use math to fight crime. O’Leary says that criminology — the study of crime and criminals — contains a lot of good math problems. “I feel like I’m in a gold mine and I’m the only one who knows what gold looks like,” he says. “It’s a lot of fun.”

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Stephen Ornes lives in Nashville, Tenn., and his family has two rabbits, six chickens and a cat. He has written for Science News Explores since 2008 on topics including lightning, feral pigs, big bubbles and space junk.

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