An anonymous reader shares a report: Investigators from Immigration and Custom Enforcement as well as the FBI have been using controversial cell-spoofing devices to secretly track down undocumented immigrants, court records show. According to a report the Detroit News, which obtained an unsealed federal search warrant affidavit, FBI and ICE agents in Michigan used a Stingray device to ensnare a restaurant worker from El Salvador in March. The devices, which were originally intended for counter-terrorism use, have come under fire because there are currently no clear rules governing when law enforcement is allowed to deploy them. Even in cases where authorities have a clear target in mind, they run the risk of exposing personal information of other innocent people in range. Until 2015, Federal investigators were free to deploy the devices without a search warrant. At that point the Justice Department laid out a policy requiring investigators get approval to use the devices first.