Drones deployed in Dorner man-hunt

US security officials have approved the first known use of drone man-hunting on American soil, with fugitive Christopher Dorner, who has a $1bn bounty on his head after killing three people, being chased by the remote-controlled tech. Customs and Border Control confirmed to Express that eye-in-the-sky technology – which is equipped with thermal-imaging cameras – had been deployed to monitor the Mexican border, where Dorner is believed to be headed.

"This agency has been at the forefront of domestic use of drones by law enforcement" spokesperson Ralph DeSio said when asked about the tracking technology. "That's all I can say at the moment."

However, an unnamed senior police source described the search as "like looking for a needle in a haystack," and suggested that the thermal cameras – which show body heat, and as such as more useful in nighttime and when broad swathes of ground must be examined – were the "only hope of finding him."

Exactly what sort of drone has been sent out in the search is unclear, though the Customs and Border Control team has been known to use a Predator model in previous incidents. Back in 2011, a high-level Predator drone operated by the agency provided valuable intelligence to a SWAT team dealing with a disgruntled, gun-toting North Dakota man, who had threatened police.

The Dorner case is the first known time when the drones – also known as UAV, or unmanned aerial vehicles – have been sent out to actively hunt a fugitive, however. Dorner, who was fired from the LAPD in 2008, has threatened a killing spree of police officers and their families, and his training in the police force and, before that, the US Navy has made him a difficult target to track.

Drone use has proved controversial in recent years, particularly the part the UAVs have played in warzones, where they have been used to deliver targeted weapons without putting manned vehicles at risk. Two separate DARPA proposals last month detailed the possible next-generation of the technology, including a high-resolution camera for improved identification, and plans to store drones underwater for rapid deployment.

They'll join an already cluttered sky, however. The Electronic Frontier Foundation (EFF) released a map of UAVs in operation last December, spanning everything from large Predator and Reaper models, down to hand-launched Raven, Puma, and Wasp drones in testing by the US Air Force.