'Grave Concerns' of Efforts to 'Track' Anti-ICE Protesters Spread After Network Anomalies Found: Report

The technology can be used to identify cell phone users in a specific area, pinpoint location or even to access personal information, text messages and phone calls.

Civil liberties advocates emphasized the potential privacy violation.

Using a Stingray device "to identify or track people exercising their First Amendment right to protest would raise grave concerns," Nathan Freed Wessler of the ACLU told SAN.

During a demonstration on July 4, hundreds of "IMSI-exposing messages" and unusual cellular rejections were recorded using a specialized detection tool. But the following day, when there was no protest, nothing abnormal was detected.

"Especially when compared to the results of the scan from the next day, the high number of IMSI-exposing messages seen during the event are strongly suggestive of the presence of an IMSI-catching device," said Patrick Traynor, a professor in the Department of Computer and Information Science and Engineering at the University of Florida.

ICE has not responded to requests for comment, and it remains unclear if a warrant to use Stingray surveillance was obtained. Federal law requires court approval to use Stingrays except in certain emergencies.

The Tukwila ICE office was vandalized during a June 14 protest, and local police used pepper spray on demonstrators.

Critics of the Trump administration have condemned White House policies described as authoritarian. ICE detention centers, like a mosquito and alligator infested camp site in the Florida Everglades, have raised alarm among human rights advocates. In June, Trump deployed marines and the National Guard in response to anti-ICE protests in California, despite objections from the Governor and LA officials.

While SAN notes, "it's not possible to definitively attribute the source of suspicious cellular activity," the timing and pattern of the network anomalies have stoked fear of deliberate surveillance of protestors.