The Chicago Police Department is being sued to turn over records regarding any purchases of cellular tracking equipment, whose use is under scrutiny by privacy activists in other parts of the country.

The plaintiff, Freddy Martinez, sought the records in a Freedom of Information request in March. The department acknowledged getting his request, but didn’t provide any information, Martinez said.

“We know that this is being deployed in other local communities,” said his attorney, Matthew Topic. “The public needs to know the extent to which this is going on.”

Martinez said he works in the software industry and advises protesters about how to keep their communications private. He said he thinks police used cellular tracking devices to monitor protesters during the 2012 NATO summit.

His lawsuit is seeking information about “international mobile subscriber identity catchers” used to identify a user on a cellular network. The products include TriggerFish, Stingray, Amberjack, Gossamer, Hailstorm, Harpoon and Kingfish.

Chicago Police investigators use TriggerFish to determine the location of cell phones in real time, sources told the Sun-Times. For instance, it’s a valuable tool to track down kidnapping victims when every second is critical, the sources said.

“If there’s an Amber Alert for a missing child, you might want to go to the TriggerFish,” one source said.

A spokesman for the city’s Law Department declined to comment because the city hasn’t yet been served with the lawsuit, filed last week in Cook County Circuit Court.

Protesters became suspicious during the NATO summit when they quickly lost power on their cell phones, Martinez said. Cellular tracking systems force phones to register with them at maximum power to retain a strong signal, he said.

“That’s when we first noticed it,” Martinez said. “A phone that would last you all day would be depleted in four hours.”

Law-enforcement agencies across the country have been using cellular trackers, according to a USA Today story published in December.

Records from more than 125 police agencies in 33 states revealed one in four used a tactic called a “tower dump,” which gives police data about the identity, activity and location of any phone that connects to targeted cell phone towers over a set period, usually an hour or two, the newspaper reported.

Email: fmain@suntimes.com