Associated Press

MILWAUKEE -- Connie Adams found it impossible to escape her ex-boyfriend.

He would follow her as she drove to work or ran errands. He would inexplicably pull up next to her at stoplights and once tried to run her off the highway, authorities said.

When he showed up at a bar she was visiting for the first time, on a date, Adams began to suspect Paul Seidler wasn't operating on instinct alone.

He wasn't. Seidler had installed a satellite tracking device in Adams' car, according to police in Kenosha, Wisconsin, 30 miles south of Milwaukee.

"He told me no matter where I went or what I did, he would know where I was," Adams testified at a recent court hearing.

Police say Adams' case and several others across the country herald an incipient danger: high-tech stalking.

Just as the global satellite positioning system can help save lives, so can its abuse endanger them, advocates of stalking victims say.

"As technology advances, it's going to be almost impossible for victims to flee and get to safety," said Cindy Southworth, director of technology at the National Network to End Domestic Violence in Washington.

In the Adams case, Seidler pleaded innocent last month to felony counts of stalking, recklessly endangering safety, burglary and a misdemeanor count of disorderly conduct. His trial is pending.

Adams does not want to speak to reporters about the case, said Susan Karaskiewicz, a Kenosha County prosecutor.

Police say Seidler put a global positioning tracking device between the radiator and grill of Adams' car. Such gadgets use a constellation of Defense Department satellites to pinpoint location and, using cellular networks, can send their coordinates to wireless handsets or computers.

Trucking companies use GPS systems to track hazardous cargo and monitor drivers. Corrections authorities use them to monitor sex offenders. Hikers, boaters and motorists use GPS devices to keep from getting lost. GPS technology is also being built into cell phones to help emergency dispatchers find 911 callers. They're also being used to prevent car theft.

Southworth trains victims advocates, law enforcement and prosecutors on stalkers' use of the technology, which she says is only just beginning to be abused.

The Stalking Resource Center at the National Center for Victims of Crime has found at least one other case of a GPS system being used to stalk a victim.

In it, a Colorado appeals court in July upheld Robert Sullivan's conviction for stalking his ex-wife and installing a GPS device in her car to track her movements.

GPS is not the first technology to be misused by stalkers -- who have also employed the Internet, microchip-sized cameras and even caller identification, said Southworth -- though it is the most dangerous to date.

Just as she once taught victims how to block caller ID when they use the phone, Southworth now suggests victims occasionally check under their car's hood.

Police are also finding GPS devices useful. Marla Wagner, sales manager at LAS Systems, the same McHenry, Illinois, company that made Seidler's device, said the company has sold GPS systems to about 10 police departments during the last year. The Kenosha Police Department is also buying a system from LAS.

Tracy Bahm, the Stalking Resource Center's director, said some states are working to update their stalking statutes to include the high-tech variety.

The center typically advises states to keep their statutes broad enough to include technologies that don't yet exist.

"As society and technology evolve, stalkers will always find new ways to harass their victims," Bahm said.

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