Feds admit they used secret anti-terror mass surveillance tool to catch an undocumented waiter

Rudy Carcamo-Carranza was an undocumented restaurant worker in Michigan wanted for a DUI and a hit-and-run; the FBI and ICE used IMSI catchers — powerful, secretive cellphone tracking tools that the agencies bill as a kind of superweapon in the war on terror — to catch him and put him up for deportation.

The existence of IMSI catchers was a closely kept secret for a long time — feds even raided a local police force to steal their arrest records to prevent the existence of the devices from being revealed in court — and their advocates have consistently said the secrecy was warranted because the tools were only used to fight the most serious crimes, and general knowledge of the tools' existence could compromise national security.

State, local, and federal law enforcement agencies have fought to conceal the details of how they use devices that impersonate the cellular communication relays widely deployed by private companies like Verizon and AT&T. The fake relays, often referred to as Stingrays, after the leading brand of such devices, can trick mobile phones into disclosing their locations, and in some cases can apparently extract the content of voice and text communications. Stingrays can be used across broad geographic areas, or as in the case of Carcamo-Carranza, to pinpoint a single person. According to an affidavit filed by the FBI's Violent Gang Task Force and obtained by the Detroit News, federal agents hoped that "locating the target cellular device will assist law enforcement in arresting Carcamo-Carranza" on the basis that he was guilty of "unlawful re-entry after deportation." The Detroit News notes that despite the involvement of the Violent Gang Task Force, Carcamo-Carranza's "only brushes with the law involve drunken driving allegations and a hit-and-run crash." Police were able to find Carcamo-Carranza's cell number after browsing his Facebook private messages, obtained with an earlier warrant. The affidavit briefly acknowledges that cell phones other than the targeted phone could be inadvertently swept up in the Stingray's dragnet.

Nathan Wessler, an attorney and technology expert at the ACLU, told The Intercept that documents show ICE has been purchasing Stingray devices for years, and presumably been putting them to use. But this case, said Wessler, is "the first time I'm aware of [Stingray] use in an actual immigration enforcement operation."

[Sam Biddle/The Intercept]