Fishermen use sonar to find the big ones and the Navy uses it to track enemy submarines. Now, law enforcement has found it can crack open cold cases.
In Oklahoma, state troopers were on the Foss Reservoir, about 110 miles west of Oklahoma City. They were training with sonar equipment from a company called Humminbird. The sonar is a more sophisticated version of the type fishermen use routinely, and can "see" down to 350 feet below the water on either side of a boat.
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To generate the image, the sonar sends out a pulse of sound and measures how much time it takes for the pulse to come back. That signal is converted into an image. Unlike the sonar that appears in old war movies, though, this type can process many images quickly. By taking a thin image - a kind of "slice" as the boat moves, like an MRI or CT scan, a built-in computer can generate fine detail.
The troopers weren't looking for anything special. Local park rangers had asked them to look at the bottom of the lake to prepare for building an extension to a marina. But when they turned on the sonar's display, they saw two old cars. The images were sharp enough that one of the troopers told a local news outlet he could see the driver side door was open.
Custer County sheriffs sent a diver to investigate the scene, where human remains were found.
The bodies might be connected to two decades-old disappearances. One was a group of local teens: 16-year-old Jimmy Williams, from Sayre, and his two friends: Thomas Rios and Leah Johnson, both 18. In November 1970 they were on their way to a football game and never came home. The second case was John Alva Porter, who disappeared in 1969. He was driving with his sister and brother-in-law. Porter was 69 at the time. A lab will test the remains for DNA and see if they can be identified.
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Sonar technology has become a lot cheaper in the last several years; Humminbird is just one company that sells it, primarily to fishermen, who want to find fish and also see any dangerous obstacles under their boats. That's what made buying the units attractive to local law enforcement - a good system can be had for under $3,000.
State troopers told local news outlets they plan to use the sonar more often - there's probably a lot more that it will turn up in lakes all over the state.
via NBC News, CNN