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Gps In The News


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REDWOOD CITY, Calif. — Scott Peterson's defense lawyer spent Wednesday morning grilling an expert who testified to the reliability of technology that police used to track the double-murder suspect before his arrest last spring.


The hearing will determine whether evidence gathered from global positioning system devices secretly placed on vehicles Peterson drove in the weeks after his wife's disappearance can be used in his upcoming trial.


Modesto police used GPS to track Peterson for nearly four months -- from Jan. 3 through April 22, 2003 -- when they arrested him near San Diego. He was caught carrying $10,000 and his brother's driver's license days after the bodies of his wife, Laci, and unborn son surfaced in San Francisco Bay.


Defense lawyer Mark Geragos wants any GPS-related evidence tossed out and has hired his own expert to question how police used it in the Peterson case. On Wednesday, he suggested that the expert called by prosecutors was motivated more by profit than justice.

"I assume you want the judge to rule that this evidence is admissable so you can sell more GPS receivers," Geragos asked in court. "Is that a fair statement?"


"I'd have to say yes to that," answered Peter Van Wyck Loomis, who's worked for Trimble, a Silicon Valley company that produces GPS receivers, since 1988.


Bound by gag orders, neither side has discussed what evidence would be lost or gained from the information gathered by the tracking devices.


The military developed the satellite-based radio navigation system, which can pinpoint a user's location at any time, in all weather, anywhere in the world. The decades-old technology is now used by everyone from airline pilots to wildlife management officials, and weekend hikers to Sunday drivers.

But GPS technology has yet to be tested in California's criminal courts. As a result, prosecutors first must establish its reliability using properly qualified experts, and then demonstrate the technology was used correctly. Only then could GPS-related evidence be introduced at Peterson's trial.


That process began Wednesday morning when Judge Alfred A. Delucchi agreed with prosecutor Rick Distaso, who said Loomis qualified as an expert.


Geragos said his client was electronically followed by GPS devices installed in vehicles he owned, borrowed and rented after Laci Peterson disappeared on Christmas Eve 2002. He wants all the GPS tracking evidence excluded from the trial.


"The GPS technology has not been generally accepted by the scientific community," Geragos said in court papers filed in October. "GPS has inherent inaccuracies."


If his claims about general GPS unreliability fail to persuade the judge, Geragos hopes to prove the device used to track Peterson was operated improperly by Modesto police, casting doubt on the accuracy of its data.


An expert hired by Geragos reviewed some of the information gathered and noted "strange occurrences" with the GPS data.


"Due to the covertness of the device, it often cannot be put in an optimal position to see the GPS satellites," wrote Michael Peach of Orion Electronics Ltd. "It may be very hard for the receiver to get signals 100 percent of the time."

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"The GPS technology has not been generally accepted by the scientific community,"


That's a lie. GPS technology is used every day by every sort of scientist. In my field it's a government-mandated requirement.


An expert hired by Geragos reviewed some of the information gathered and noted "strange occurrences" with the GPS data.


Yes, I don't doubt that, especially when analizing track files. There's probably some wild jumps as the vehicle went under bridges, around trees and tall buildings, and even on cloudy days. There may even be gaps in the track file.


I think it is possible, even with a bunch of crazy bounces, to show the overall path that the vehicle traveled. It's up to lawyers and the courts to decide how many boomerangs make track files too unreliable to be used as court evidence.



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