CHEYENNE, Wyo. (AP) -- Authorities say an investigation into reports of large drones flying in groups after dark since November has confirmed nothing unusual or criminal.
They're mostly hobbyist drones, commercial aircraft, stars, planets and weather phenomena.
Yet if history is any guide, the investigation involving flights of a heat-detecting plane in northeastern Colorado will settle nothing for many people. They've also been seen in Nebraska and Wyoming.
The Colorado Department of Public Safety said Tuesday it will scale back flights of a heat-detecting plane to try to corroborate reports as they're made but will continue to look into new reports.
Law enforcement agencies in eastern Colorado and much of Nebraska have been taking calls about unusual drone sightings for over a month. Drones as big as cars have been said to fly back and forth after sundown.
Dan Carlson says drones have flown after dark near his Nebraska farm four times this year. He suspects military involvement. U.S. Air Force officials overseeing dozens of nuclear missiles scattered across the region deny any role in the drone sightings.