A man accused of snatching an Apple iPhone from a woman's hand in San Francisco was arrested just nine minutes later - because the device tracked his every move.
The iPhone was being used to test a new, real-time global positioning system (GPS) tracking application and the woman holding it was an intern for the software's maker, Mountain View-based Covia Labs.
Covia chief executive David Kahn had sent the intern into the street to demonstrate the software.
Police say Horatio Toure snatched it and sped away on a bicycle, according to the San Francisco Chronicle.
Mr Kahn was watching a live map of the phone's location on a computer and says he was immediately struck by how quickly the image began moving down the street.
Police arrested Toure nine minutes later.