Last month, 14-year-old Ashley Barbour of Colville, Washington took off with a guy she'd met online. Monday police found her - using a license plate recognition system in which police cars routinely photograph and store thousands of license plate numbers while on patrol - with time stamps and locations.
Using that database, once they had the suspect's plate number his car's movements appeared as a series of dots on a Google map, heading for Idaho.
But here's what else the system can do: "We have a series of four shootings, and we have dates and locations for all of the incidents."
That's from a demonstration video from Vigilant Solutions. Now suppose the only clue to the shootings is that a witness noticed the word Metro on the license plate frame. Not much to go on.
But police cars have been automatically scanning license plates on their patrols.
So a detective can enter the four shooting locations on a Google map, and within second, get a list of all license plates spotted in those four areas at the approximate time of the crimes.
"In this case, two common plates were found. One was seen at three of the locations. The other was seen at only two of the four," according to the demonstration.
Choose the license plate that was seen most frequently, and zoom in to an actual picture stored in the database.
"Enlarging one of the vehicle's images the word 'metro' is clearly seen on the license plate frame."
Bingo. Somebody's about to get a knock on the door.
Civil libertarians want limits on this, because it's not much different than what the NSA is doing with phone records.
But if it can help track down the bad guy ...