How new underwater sonar is helping solve decades-old cold cases

Police officers in southwestern Oklahoma appear to be on their way to solving a pair of decades-old cold cases while learning how to use new sonar imaging equipment on a remote lake. Sonar itself may be decades old, but the imaging system that the cops were using is state of the art — and the technology is finally affordable enough for local police units to give it a try.

Sonar works by sending pulses of sound waves out into the water and recording the waves that bounce back to create an image. A new type of imaging technique, one that works in a similar way to an MRI scanner at a hospital, is finally becoming affordable enough to put into portable devices.