GPS devices aid prosecutors' efforts
Help to establish whereabouts of several defendants
TAMPA - Like millions of motorists, Eric Hanson used a GPS unit in his Chevrolet TrailBlazer to find his way around. He probably didn't expect that prosecutors would eventually use it too - to help convict him of killing four family members.
Prosecutors in suburban Chicago analyzed data from the
Hanson's trial was among recent criminal cases around the country in which authorities used GPS navigation devices to help establish a defendant's whereabouts. Experts say such evidence will almost certainly become more common in court as GPS systems become more affordable and show up in more vehicles.
"There's no real doubt," said Alan Brill, a Minnesota-based computer forensics expert who has worked with the FBI and Secret Service. "This follows every other technology that turns out to have information of forensic value. I think what we're seeing is evolutionary."
Using technology to track a person's location is nothing new. For years, police have been able to trace cellphone signals and use other dashboard devices such as automatic toll-collection systems to confirm a driver's whereabouts.
But the growing popularity of GPS systems - in cars, cellphones, and other handheld devices - gives authorities another powerful tool to track suspects.
Developed for the military, GPS navigation systems started showing up in cars in the 1990s. Prices have dropped sharply in the past few years, and many units are now available for less than $150.
The Consumer Electronics Association estimates 20 percent of American households own a portable GPS system and 9 percent have vehicles equipped with in-dash systems.
A GPS unit receives signals from satellites to determine its position on the ground. That data can be used by mapping software to display the device's location to within a few yards.
Detectives are often able to extract map searches and desired destinations that have been entered into a GPS unit by the user. Some devices are equipped with a "track back" feature that can show where the unit was at a particular time.
"What we're dealing with here is a use of the technology that I don't think the good people at Magellan or Garmin or TomTom really thought about when they were developing it," said Brill, referring to manufacturers of GPS devices.
Law enforcement sometimes uses secretly planted GPS devices to monitor suspects. The practice, often done without a warrant or court order, has been criticized by privacy advocates who argue that it is unconstitutional.
The GPS feature on a cellphone has helped solve at least one crime. In 2006, police in Virginia Beach, Va., used the GPS on a homicide victim's cellphone to find the phone and her purse behind a home. The home was linked to the man who was eventually charged with killing her.