You might not notice the cameras mounted on the back of one Strongsville police cruiser as you go by, but they'll see you.
The Automatic License Plate Reader grabs a picture of every vehicle it passes, sending the numbers to a database to see if there's any reason police should stop your car.
"On a good day, it'll run 1,000 plates on a shift," said Officer Dan McNeal, who often drives the cruiser on road patrol.
The $16,000 unit, which came to Strongsville through a grant from Cuyahoga County, is designed to seek out stolen vehicles, missing people and those with arrest warrants, Chief Jim Kobak said.
It sends license plate numbers to a regional data sharing system and sounds an alert if there's a hit.
"The main purpose was originally to find stolen cars," Deputy Chief Tony Zacharyasz said.
But the units are now also used to see if the owner of a passing car has a warrant. McNeal said he's been able to stop and arrest drivers on warrants after the unit gives an audible alert.
And Zacharyasz said it also helped when the family of an older Strongsville resident reported her missing.
After Strongsville sent out a missing person alert, a Cleveland police officer saw that his license plate reader had spotted the woman's car earlier in the day, recording the exact time and location.
"We were able to use that to find out she wasn't missing -- she was fine and visiting family in Cleveland," Zacharyasz said.
The device can be mounted on a stationary object, like on a utility pole or under a bridge, or can be carried in a police vehicle.
In Strongsville, two cameras are mounted on the trunk of a patrol car, one facing forward and one facing back to capture information on every vehicle it passes.
The cameras can photograph thousands of license plates per minute.
The readers have come under fire from the American Civil Liberties Union, which worries that the devices will jeopardize Americans' privacy.
According to the ACLU's website, law enforcement agencies can create databases that track and store the location of every motorist who encounters the system, not just those suspected of criminal activity.
It then "becomes a warrantless tracking tool, enabling retroactive surveillance of millions of people," the website says, including someone's visits to churches and doctors' offices.
Zacharyasz said some people put covers over their license plates with mirror-type reflectors to try to throw off the cameras.
"I imagine most are law-abiding citizens who just don't like the idea of Big Brother watching them," he said.
Many area police departments, including Brunswick, Hinckley, Berea and Middleburg Heights, also have license plate readers.
The ALPRs have been used by law enforcement agencies in northeast Ohio for at least two years.