Conspiracy theories abound despite officials' denial of drone invasion So far, a search has uncovered zero evidence of suspicious activity.

Scroll through any one of the many Facebook groups dedicated to tracking the mysterious drone sightings over Colorado and Nebraska, and you'll find no shortage of people convinced they're seeing something.

"We just counted 30 drones/UAVs/UFOs over Haxtun," wrote one man.

"In Kearney, NE about 8 traveled through from the west," said another.

"Swarms of them," someone posted about drones circling Denver. "They seemed to be making a circular pattern around the city."

Concerned calls from residents worried about secret government spying and invasions of privacy prompted local sheriff's departments to set up a task force this week, teaming with federal and state agencies to try and get to the bottom of the drone sightings.

So far, they've found nothing. Officials told ABC News their search has yielded zero evidence of suspicious drone activity.

Colorado even sent its high-tech surveillance plane airborne on Monday night. The Multi-Mission Aircraft, or MMA for short, normally tracks the spread of wildfires and is equipped with sensitive cameras and sensors that can see through smoke. The MMA flew a spaghetti-like pattern above northeast Colorado for nearly five hours.

"The MMA has the capability to detect heat signatures; it did not detect any suspicious heat signatures or drones related to the drone reportings during its flight," said a Colorado Department of Public Safety statement on Thursday.

Officials have suggested people who think they're seeing drones may actually be seeing something else.

"Several of the reports resulted in verified aircraft," said Micki Trost, spokeswoman for the Colorado Division of Homeland Security and Emergency Management.

Many people insist that's not the case.

"We have lived here long enough to know these are not airplanes, we have been on our upper deck in the evenings enough times to know these are not airplanes," a woman wrote on Facebook.

Another man reported seeing a drone go down in flames in Logan County, Colorado. But deputies searching the area found nothing and suggested he had actually seen a meteor or a shooting star.

Another theory is that the initial sightings reported in mid-December were not drones at all, but a constellation of recently-launched SpaceX global internet satellites known as Starlink. The satellites, which look like a line of dots in the sky, would have been visible beginning the evening of Dec. 18, and they would have appeared brighter than Venus, according to the satellite tracking website Heavens Above.

That's not to say there aren't still a few drones out there somewhere that could potentially be dangerous.

Thursday night, the Colorado Department of Public Safety said a report of a drone coming within 100 feet of a medical helicopter “has increased concern around reports of suspicious drones in northeastern Colorado.”

The agency said it would activate resources that might include the use of teams on the ground and in the air, and posted a frequently asked questions document about suspicious drone activity.

Online, theories abound and stretch the imagination. Some insist the drones must belong to the military searching for a lost nuclear warhead, to DEA agents looking for houses illegally growing marijuana, or, yes, to aliens.

"It almost seems like drones are taking over the mass hysteria of UFOs and Sasquatch sightings. The difference here is that these are not aliens," said Col. Steve Ganyard, a former Marine fighter pilot and ABC News consultant. "They're probably your neighbors flying their drones at night."

Government denials and statements haven't helped. The Phillips County Sheriff on Monday said authorities were looking for a "command vehicle," describing it on Facebook as a "box trailer with antennas or a large van."

By Wednesday, however, the department said that vehicle was no longer relevant and would no longer make any new statements about drones, prompting some to suggest the department was ordered to keep quiet.

"Everyone loves conspiracy theories," said psychologist Susan Krauss Whitbourne, a professor emerita at the University of Massachusetts Amherst.

In the sometimes fact-challenged echo chamber of social media, Krauss Whitbourne said people are having their beliefs and biases confirmed, even in the face of mounting evidence to the contrary.

"When there's something potentially harmful about the government's attempts to hide the facts from you, it does stoke the fire," Krauss Whitbourne said. "Those who slant a little bit more toward the cynical side will start to question anything that they're told that counters their ideas."

While there may be no way to counter conspiracy theorists, Krauss Whitbourne said, the best tactic may be to ignore them.

"The harder that Colorado tries to say this isn't true, it provides attention," she told ABC News. "By ignoring the extremists, you're dampening their enthusiasm. Because what they want is that attention, and confirmation of their views."

Officials said they aren't abandoning the search for mystery drones entirely. The truth may still be out there.

"We will continue to work with the joint operation of local, state and federal agencies," Trost said, "as long as members of the community continue to report suspicious activity."