Police Use GIS in D.C.–Area Sniper Case and More

Anna Brendle
for National Geographic News
November 20, 2002

Today, November 20, is GIS Day. Geographic Information Systems, once a tool used solely by mapmakers is gradually going mainstream, found in automobiles for driving directions, used by real estate agents to track home sales, and by police departments to solve crimes.

A tool once used only by geographers is gradually becoming an invaluable asset to police departments around the country.

Geographic profiling, using Geographic Information Systems (GIS), helps police track crime, determine where criminals might live or work, trace cell phone calls, and more.

Before GIS, detectives used paper maps to track criminals with colored pinpoints. "It would take four or five people a week to update those old pin maps," said Keith Harries, a professor of geography at the University of Maryland, Baltimore County. "As soon as it was done, it was out of date."

At least 13 percent of the police departments in the U.S. are now using GIS to solve crimes, and more importantly, to prevent them, according to the National Institute of Justice (NIJ).

"GIS has fundamentally altered the way we view crime and contributing factors to crime," said Jim Bueermann, chief of police in Redlands, California. "It gives investigators an analytical tool that was heretofore unavailable."

Geographic profiling links databases that contain information such as addresses, timelines, crime incidents, land uses, and street locations with mathematical models about criminal behavior to detect patterns, trends, and clusters of criminal activity.

Investigators are even using GIS to map an offender's methods and behaviors to produce maps tracking crime in almost real time.

"We used to have to link reports together in our heads," said Bueermann. "Its very tough when the geography is complicated and offenders are moving around quickly."

Geographic Profiling in the Recent Sniper Case

The manhunt for the snipers who terrorized the Washington, D.C. area in October is a high-profile instance of police using GIS to link 13 separate attacks that occurred over the course of several weeks and in several states.

Once the sniper suspects were arrested, geographic profiling efforts turned retrospective, as crime analysts from across the U.S. convened at NIJ. The researchers worked "to examine what was done, how it was done, and to come up with a model to be applied in other jurisdictions," said Phil Canter, statistical analyst at the Baltimore County Police Department and one of the participants.

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