Armed with a search warrant, Nelson County Sheriff Kelly Janke went looking for six missing cows on the Brossart family farm in [eastern North Dakota]. He called in reinforcements from the state Highway Patrol, a regional SWAT team, a bomb squad, ambulances and deputy sheriffs from three other counties. He also called in a Predator B drone. Sophisticated sensors under the nose helped pinpoint the three suspects and showed they were unarmed. Police rushed in and made the first known arrests of U.S. citizens with help from a Predator, the spy drone that has helped revolutionize modern warfare. But that was just the start. Local police say they have used two unarmed Predators based at Grand Forks Air Force Base to fly at least two dozen surveillance flights since June. The FBI and Drug Enforcement Administration have used Predators for other domestic investigations, officials said. The drones belong to U.S. Customs and Border Protection, which operates eight Predators on the country's northern and southwestern borders to search for illegal immigrants and smugglers. The previously unreported use of its drones to assist local, state and federal law enforcement has occurred without any public acknowledgment or debate.