WASHINGTON - Someone was attacking women in Northern Virginia, grabbing them from behind, and sometimes punching and molesting them before running away. After logging 11 cases in six months, police finally identified a suspect.
David Lee Foltz Jr., who had served 17 years in prison for rape, lived near the crime scenes. To figure out whether Foltz was the assailant, police pulled out their secret weapon: They put a Global Positioning System device on Foltz's van, which allowed them to track his movements.
Police said they soon caught Foltz dragging a woman into woods in Falls Church, Va. After his arrest on Feb. 6, the string of assaults suddenly stopped. The break in the case relied largely on a crime-fighting tool they would rather not discuss.
"We don't really want to give any info on how we use it as an investigative tool, to help the bad guys," said Officer Shelley Broderick, a Fairfax, Va., police spokeswoman.
Across the country, police are using GPS devices to snare thieves, drug dealers, sexual predators, and killers, often without a warrant or court order.
Privacy advocates said tracking suspects electronically constitutes illegal search and seizure, violating Fourth Amendment rights, and is another step toward George Orwell's Big Brother society.
Law enforcement officials, when they discuss the issue at all, said GPS is essentially the same as having an officer trail someone, just cheaper and more accurate. Most of the time, as was done in the Foltz case, judges have sided with police.
With some courts supporting the tactic and the declining cost of the technology, many analysts believe that police will increasingly rely on GPS as a tool in investigations. Last year, FBI agents used a GPS device while investigating an embezzlement scheme to steal from D.C. taxpayers, attaching one to a suspect's Jaguar.
"I've seen them in cases from New York City to small towns - whoever can afford to get the equipment and plant it on a car," said John Wesley Hall, president of the National Association of Criminal Defense Lawyers. "And of course, it's easy to do. You can sneak up to a car and plant it at any time."
Details on how police use GPS usually become public when the evidence is challenged in court. Such cases have revealed how police in Washington state arrested a man on a charge of killing his 9-year-old daughter: the GPS device attached to his truck led them to her body.
Cases have shown how detectives in New York caught a drug-runner after monitoring his car as he bought and sold methamphetamine. In Wisconsin, police tracked and caught two suspected burglars by attaching a GPS device to their car.
The Foltz case offers a rare glimpse into how a Washington area police department uses GPS.
Foltz's attorney, Chris Leibig, challenged police in court last week and tried to have the GPS evidence thrown out.
He argued at a hearing at Arlington County (Va.) General District Court that police needed a warrant because the device tracked Foltz's vehicle on private and public land.
The judge disagreed, and the evidence will be used at Foltz's trial, which will begin Oct. 6. Foltz was charged in the Feb. 6 attack, but not in the others.
GPS advocates said police do not need a warrant to track suspects electronically on public streets because the device provides the same information as physical tracking.
"A police officer could do the same thing with his or her own eyes," said Richard E. Trodden, the Arlington commonwealth's attorney. "It helps to cut down on the number of police officers who would have to be out tracking particular cars."
Leibig said GPS should be held to a different standard because it provides greater detail.
"While it may be true that police can conduct surveillance of people on a public street without violating their rights, tracking a person everywhere they go and keeping a computer record of it for days and days without that person knowing is a completely different type of intrusion," he said.
© 2008 The Washington Post