Federal agencies fly drones to assist in disasters, check flood damage, do crop surveys and more. U.S. Customs and Border Protection flies the largest fleet, 10 unarmed Predators, along the northern and southern borders to help track smugglers and illegal immigrants.
Although flying drones might appear as easy as playing a video game, pilots and crews require extensive training.
In 2004 and 2005, the U.S. Marshals Service tested two small drones in remote areas to help them track fugitives, according to law enforcement officials and documents released to the ACLU under the Freedom of Information Act. The Marshals Service abandoned the program after both drones crashed.
Except in rare cases, the military is barred from using drones in U.S. airspace to conduct surveillance or pursue individuals. No state or federal agency has proposed arming domestic drones with weapons, but the prospect has raised alarms in Congress and elsewhere.
In response to a question during an online Google chat Thursday, President Obama said drones had never been used to kill "an American citizen on American soil."
"The rules outside of the United States are going to be different than the rules inside the United States, in part because our capacity, for example, to capture terrorists in the United States are very different than in the foothills or mountains of Afghanistan or Pakistan," Obama said.
No drone was sent up to help find suspected killer Christopher Dorner after his truck was found burning near Big Bear Lake on Feb. 7, said Al Daniel, an officer in the aviation division of the San Bernardino County Sheriff's Department. But Customs and Border Protection transmitted secure video from a Pilatus PC-12 plane to police commanders on the ground.
Despite a massive manhunt, Dorner vanished and authorities speculated he had escaped to Mexico. Five days later, however, he was found in a snowbound cabin near his truck and died after a shootout and fire.
The long delay, and the embarrassing fact that Dorner was hiding close by the police command post, sparked sharp criticism of police tactics and abilities.
Steve Whitmore, a spokesman for the Los Angeles County Sheriff's Department, said an aerial drone might have helped find Dorner more quickly.
"The search would have been much wider and quicker because you'd have an unmanned aircraft looking," he said. "You can cover more ground."
Bennett reported from Washington and Rubin from Los Angeles. Times staff writer Robert Faturechi in Los Angeles contributed to this report.