Acting head of US Immigrations and Customs Enforcement Thomas Homan told US Senator Ron Wyden the agency does not use cell-site simulators -- a type of surveillance gear often referred to as a "Stingray" that can track down a specific mobile device by emulating mobile phone towers -- to locate undocumented immigrants.
Per Ars Technica, the August 16th letter states ICE Enforcement and Removal Operations "does not use cell-site simulators for the purpose of civil immigration law enforcement." But he added that ICE's Homeland Security Investigations division, which targets national security threats and organised crime, uses the devices, though only after receiving a warrant.
Homan also noted that ICE agents sometimes work in joint task forces with other "federal, state and local law enforcement partners, in furtherance of our shared public safety mission" -- and that in those cases, Stingrays may sometimes be used.
That caveat is important: In March, ICE used a Stingray variant known as a Hailstorm to locate 20-year-old El Salvadorean man Rudy Carcamo-Carranza, who had entered the US illegally twice and was wanted in connection to alleged drunk driving and hit-and-run incidents. The ICE officer involved in the investigation, Jeremy McCullough, was a member of the ERO department but was also assigned to the FBI's Violent Gang Task Force. So for ICE agents to use a cell-site simulator to track people suspected of immigration law violations, they just need to be assigned to such a unit.
Wyden had asked ICE a number of questions about its use of the devices in May, though Homan's letter does not appear to have totally addressed all of them.
Cell-site simulators are controversial law enforcement tools because they spoof a regular base transceiver station, tricking all cellular devices in the area into connecting to it. While they allow police to track down a specific person (or at least their mobile device) almost instantly, they can only do so by casting a large dragnet. In the process of spoofing the signal, Stingray devices can interfere with network access, including in some cases disrupting emergency calls.
Homan's letter, however, insisted that the devices refer "non-targeted mobile hardware" back to regular networks "in an amount of time that is not noticeable to the user," saying interference only occurs if someone is dialling a number at the exact time the device is switched on.
"In all circumstances, devices are always able to dial 911 without any disruption of service," it continued.
In the era of President Donald Trump, ICE has ramped up its efforts to go after the undocumented population. From January to June 2017, the agency made 75,045 administrative arrests of undocumented immigrants and deported 105,178 -- the arrest total being some 40 per cent higher than 2016, though deportations were actually down.