BALTIMORE (WJZ) — A wild chase down Interstate 95 ends with a crash. Police got on the trail of the stolen car using controversial technology increasing across Maryland.

Adam May has an exclusive look at the police tool in action.

These days cameras are everywhere, but some do more than watch–they automatically run criminal records.

At the height of Tuesday’s rush hour, police chased a New Jersey car thief–alerted when he raced through the Fort McHenry Tunnel.

“Set off an automatic sensor that detected the plates were on a stolen vehicle,” said Captain Jeff Long, Sky Eye Chopper 13.

Those sensors are called automatic license plate readers, or LPRs. WJZ got an exclusive look at how they work.

“We’re looking for this Mercedes,” said Lt. Craig Hartman, Baltimore Police.

Specially assigned police officers have LPRs mounted on their cars.

“Looks like one of our guys got a hit,” said Det. Brian Ralph, Baltimore Police.

Detective Brian Ralph can scan up to 3,000 tag numbers a shift, searching for stolen vehicles and violent criminals.

“So if someone is looking for a particular vehicle in reference to a robbery or murder or something like that, we can put that tag number into the system and it will hit if the vehicle happens to drive by,” said Hartman, Regional Auto Theft Task Force.

More than 320 LPRs are in use across Maryland. Information about every scanned license plate–even non-criminal–is stored at the Maryland Coordination and Analysis Center. That concerns the ACLU.

“As the data increases over time you get a more detailed picture of Marylanders’ movements. And that is information the government has no business knowing, absent some particular law enforcement need,” said David Rocah, ACLU.

But police say storing information could help in future cases, and the LPRs are way more effective than the naked eye.

“It’s really hard to see the tags for what we do every day and this LPR doesn’t miss a thing,” said Ralph.

It tracks the moves of tens of thousands of Marylanders every single day.

Police are trying to get funding for more plate readers, but the debate over storing the information remains unresolved.

Last month, a New York man–wanted for murder–was caught by a license plate reader on Interstate 95.