And that’s just one of the ways bad guys are putting drones to use, law enforcement officials say. DENVER, Colorado — Last winter, on the outskirts of a large U.S. city, an FBI Hostage Rescue Team set up an elevated observation post to assess an unfolding situation. Soon they heard the buzz of small drones — and then the tiny aircraft were all around them, swooping past in a series of “high-speed low passes at the agents in the observation post to flush them,” the head of the agency’s operational technology law unit told attendees of the AUVSI Xponential conference...