The vehicle showed no signs of suspicion, and, Cpl. Chad Jones said, he might have patrolled right past it without the ever-attentive “eyes” atop his squad car.

Scanning each vehicle Jones passed in an Albertsons parking lot, the license plate reader pegged the Dodge pickup as one reported stolen a few weeks earlier in Houston. Jones’ laptop matched the plate in a national database of stolen cars, and an electronic voice reported the “high-priority alert” to the East Baton Rouge Parish sheriff’s deputy.

Jones said he arrested the driver on unauthorized use of a motor vehicle shortly after she left the grocery store.

“Without this system, that car would not have been caught that day,” Jones said of the cameras mounted near his emergency lights. “This is a huge tool for us.”

State and local law enforcement officials said they are increasingly turning to automatic license plate readers to find stolen vehicles and track the movements of criminal suspects.

The technology, often provided by state and federal grants, has enhanced investigators’ ability to solve crimes and share information across agencies, authorities said.

The cameras, which photograph thousands of vehicles a day, have also raised privacy concerns as organizations such as the American Civil Liberties Union seek clarity on how law enforcement is using the images.

Agencies across the Baton Rouge area are using license plate readers attached to one or more patrol vehicles, while State Police have installed stationary cameras in strategic immobile locations across the state over the past year.

The cameras have identified vehicles “that we knew were involved in bank robberies, allowing officers to set up and make an arrest,” said Capt. Doug Cain, a State Police spokesman.

“It provides us the ability to quickly identify vehicles of interest, whether it’s stolen vehicles, fugitives we’re actively looking for, manhunt situations, missing persons or Amber alerts,” Cain said.

He declined to disclose the locations of the cameras or say how many the agency has, but said they “touch most of the state in some form.”

Employing technology

License plate readers typically rely on optical character recognition and infrared lighting. They automatically check plates for outstanding warrants without an officer having to key in the plate code or to contact dispatch.

The Baton Rouge Police Department, among the first in the state to adopt the technology, now uses seven license plate readers, some of which are on marked vehicles while others are used “covertly,” police spokesman Lt. Don Kelly said.

The department has not mounted any stationary readers in the city, he said. The mobile readers on the police cars check for outstanding warrants but do not run the registration, Kelly said.

Baton Rouge police credit the cameras — purchased for about $19,000 each with state or federal grants — for the recovery of more than 300 stolen vehicles, 250 stolen plates and some 250 arrests since 2008.

“They have also helped us locate over 50 wanted felons and several missing persons, and have been instrumental in many investigations of serious crimes, including murders, rapes and robberies,” Kelly said.

The department keeps the data for about a year as an investigative resource, he said.

“Let’s say a robbery takes place and a witness gives us a license plate number of a car observed fleeing the scene,” Kelly said. “We may be able to go search back in our system and find a photograph of that actual car taken several months earlier that could be circulated to our officers so they can be on the lookout for it.”

Privacy concerns

The cameras are not without their critics.

The ACLU requested information about them last year from law enforcement in several states, including Louisiana.

“If used for the sole purpose of recovering stolen vehicles and identifying people who break traffic laws, it can be a useful tool for law enforcement,” said Marjorie R. Esman, executive director of the ACLU of Louisiana. “If kept and used to see what car is where, it can be a violation of the privacy of law-abiding people.”

While there is no expectation of privacy on a public road, Esman said, “People have the right to expect that the government is not storing information about where they go and when they go there.

“That, essentially, can become a warrantless search, and could be used for improper purposes,” she added.

Only a few authorized employees at the Baton Rouge Police Department have access to the photos, which are stored on a secure internal server, Kelly said.

“As far as I’m aware, it’s never been hacked or abused,” he added.

The cameras capture only images of cars with their license plates visible, Kelly stressed.

“It’s no more intrusive than if someone driving down the street or standing in a parking lot took pictures of cars as they pass,” he said. “Even in the absolute worst-case scenario, if someone did manage to get into the system, all they would find is lots of boring photos of the backs of vehicles.”

Differing capabilities

The systems vary from agency to agency, and each has its limitations.

The system used by two East Baton Rouge Parish sheriff’s units does not differentiate among states when scanning plate codes, requiring deputies to verify the state when the system finds a “hit.”

Jones’ system has side cameras that can scan rows of parked vehicles and a rear camera angled to see vehicles passing him in the opposite direction. He said the system struggles with motorcycle plates and will not read tags from Delaware.

“They still need me right now because I’ve got to turn it on,” Jones quipped.

License plate readers also are being used in small police departments in communities such as Zachary and Baker.

A recent survey by the Police Executive Research Forum found that “almost every police agency expects to acquire or increase their use of LPRs in coming years, and that five years from now, on average they expect to have 25 percent of their cars equipped with LPRs.”

At LSU, police have two license plate readers mounted on patrol vehicles and one stationary camera on campus connected to the National Crime Information Center and the 19th Judicial District Court, said Capt. Cory Lalonde, a department spokesman. The cameras can read up to 10,000 plates per hour and store two photographs of each plate — along with a location determined by GPS — for six months.

In 2012, LSU police had 31 arrests involving a license plate reader that received an alert from the system, mostly for traffic offenses, Lalonde said.

“An important part of our job in serving the LSU community and keeping that community safe is knowing who is coming into that community, as well as passing through,” Lalonde said, adding the department plans to purchase more stationary cameras once funding is available.

During a recent homicide investigation, deputies in Ascension Parish asked St. James Parish authorities to pull photos of every license plate that had passed a stationary reader on La. 70 around the time of the killing, said Maj. Ward Webb, of the Ascension Parish Sheriff’s Office.

Though the investigation moved in a different direction, Webb said, “those are the types of the things that the system can do for us.”

Ascension Parish recently began using one license plate reader mounted to a deputy’s vehicle, part of a pilot program through the National Public Safety Consortium, Webb said.

The consortium’s chairman, Jonathan Miller, said four Louisiana parishes — Ascension, Terrebonne, Allen and Lincoln — are participating in the program, while another 17 have expressed interest in the technology.

Miller said the readers provided by the consortium recognize wanted plates as well as uninsured vehicles, but they do not store any images.

“A law-abiding person and their vehicle is invisible to this system, and that’s really important,” Miller said. “We just don’t want to have a privacy fight on our plate.”

Louisiana Insurance Commissioner Jim Donelon said the readers have helped reduce the rate of car theft in the state.

“While it’s a pretty well-kept secret among the general population, I think the key to the success is that it’s a well-known fact among the population that would engage in car theft,” Donelon said.

Residential use

The technology also is making its way into the private sector. Leland Wolf, president of Latech Security, said his company plans to market affordable stationary license plate readers to Baton Rouge homeowners’ associations in the near future.

“What that’s going to do is offer them the ability to track potential burglars going in and out of their neighborhood,” Wolf said. “It would be a win-win for both the homeowners association and the police department.”

Baton Rouge police made an arrest as recently as Friday morning that they attributed to a license plate reader.

The camera system alerted a patrolling officer to a wanted Chevrolet Camaro on Airline Highway, Kelly said.

The officer followed the vehicle, confirmed the warrant — an embezzlement charge out of Gulfport, Miss. — and pulled over the driver, Derrian Devine, 25, for a traffic violation, Kelly said.

“Without LPR,” Kelly said, “we would have never known he was in Baton Rouge.”