A routine information request by the ACLU for public records regarding the use of a surveillance tool known as "Stingray" from the Sarasota, FL., police department prompted a raid from the US Marshals Service - the raid was not part of some sting operation on local drug lords, but was instead carried out on the police department in order to halt the release of the documents requested.

According to Wired, the ACLU had an appointment to review documents pertaining to a case investigated by a Sarasota police detective. But marshals swooped in at the last minute to grab the records, claiming they belong to the U.S. Marshals Service and barring the police from releasing them.

ACLU staff attorney Nathan Freed Wessler called the move “truly extraordinary and beyond the worst transparency violations” the group has seen regarding documents detailing police use of the technology.

“This is consistent with what we’ve seen around the country with federal agencies trying to meddle with public requests for stingray information,” Wessler said, noting that federal authorities have in other cases invoked the Homeland Security Act to prevent the release of such records. “The feds are working very hard to block any release of this information to the public.”

Stingrays, also known as IMSI catchers, simulate a cellphone tower and trick nearby mobile devices into connecting with them, thereby revealing their location. A stingray can see and record a device’s unique ID number and traffic data, as well as information that points to its location. By moving a stingray around, authorities can triangulate a device’s location with greater precision than is possible using data obtained from a carrier’s fixed tower location.