U.S. Immigration and Customs Enforcement (ICE) paid $825,000 earlier this year for vehicles equipped with cellphone-tracking technology, according to public records reviewed by TechCrunch.

The May 8 contract was awarded to TechOps Specialty Vehicles, a Maryland-based company, to provide “Cell Site Simulator (CSS) Vehicles” that can act as fake cellphone towers to locate nearby phones. The technology allows law enforcement to identify or track individuals’ devices in real time.

TechOps president Jon Brianas told TechCrunch he could not discuss details, citing “trade secrets,” but confirmed his company integrates such technology into its vehicles. “We don’t manufacture electrical, comms, and technology components, we integrate that product into our overall design of the vehicle,” he said.

Cell-site simulators, also known as “stingrays,” mimic cellphone towers to trick phones into connecting to them. Civil rights groups have long raised privacy concerns about their use, saying the devices can capture data from innocent bystanders.

According to documents obtained by the ACLU, ICE used these devices at least 466 times between 2017 and 2019 and nearly 1,900 times between 2013 and 2017.

ICE did not respond to TechCrunch’s specific questions about how the vehicles are used or whether the agency obtains warrants for each deployment.

The new contract marks one of several federal agreements expanding the use of mobile surveillance technology. Critics say the lack of transparency surrounding such tools raises major questions about privacy and civil liberties.