UFOs aren't often discussed in Washington, D.C., and former members of Congress don't often hold hearings.

But that's what's happening this week at the National Press Club, where the UFO advocacy group Paradigm Research has paid $20,000 each to former Sen. Mike Gravel and former Reps. Roscoe Bartlett, Merrill Cook, Lynn Woolsey, Carolyn Kilpatrick, and Darlene Hooley, all Democrats, to stage a five-day "hearing" modeled after congressional proceedings to examine evidence of UFO sightings and the possibility of advanced extraterrestrial life. The program has an eye toward government disclosure of whatever the military and intelligence communities may know about the subject.

To say that conspiracy theories abound at this event would be an understatement. On Wednesday, UFO experts said they were certain of a government cover-up.

The former lawmakers heard from Peter Davenport, director of the National UFO Reporting Center, who recounted eyewitness reports of unidentified flying objects, hovering motionless and able to change direction more quickly than earthly technologies would seem to allow.

In McMinnville, Tenn., in 1995, observers witnessed a fleet of hovering objects, and a cluster of the lights appeared to explode. In 1997, residents of Phoenix witnessed at least one "unimaginably" large craft hovering over the city. In 1999, two airline pilots near the Dallas-Fort Worth airport saw a large disc approach their plane and execute a 120-degree turn in less than one second, Donovan said.

"I have no explanation for a craft that can hover motionless above Phoenix for five minutes," Davenport told the panel.

They also heard from Peter Robbins, a researcher and lecturer, who told them of sightings like the Rendlesham Forest Incident in the U.K., where U.S. Air Force personnel said they witnessed a UFO, and Gary Heseltine, a former U.K. police detective, who has collected sightings from police officers.

"I now have over 425 cases involving over 940 British police officers," Heseltine told the panel. "Over 70 percent of these cases are multiple-witness-officer cases."

Linda Moulton Howe, a journalist who studies livestock mutilation, brought slides of horses and cattle that had been stripped of flesh, had their organs removed surgically and without any trace of blood, and were left on soft patches of earth without any surrounding tracks.

"Ranchers have seen the glowing discs put beams down. Ranchers have seen the animals rise," Howe said, showing a cow with its udder cleanly removed, no blood in sight. Howe clicked to another slide of cow flesh bearing serrated cut marks that university veterinarians told her had likely been done with equipment using high heat.

"I think it involves, on a more sophisticated level, what we are beginning to do in our science with cloning," Howe said, when former Rep. Lynn Woolsey asked, skeptically, what extraterrestrials might want with cow parts. "The agencies of the U.S. government, the CIA … they've all been studying this. They have more data than I do."

The lawmakers appeared partially swayed, but not sold on the idea that extraterrestrial beings have used advanced technology to visit Earth and lift animals from fields with beams - and that multiple world governments have been silent.

"I'd have to be pretty arrogant to think that, out there in this huge universe, there isn't some civilization more advanced than ours," Bartlett said.

"Isn't it a leap to say, 'UFOs exist,' and then say it's E.T.?" asked Cook. "Is it the only explanation?"

Woolsey told ABC News she agreed to appear on the panel because she's interested in government transparency.

Gravel, the former Democratic Alaska senator who ran for president in 2008, told ABC News he doesn't believe UFO sightings necessarily mean extraterrestrial life exists.

"We don't know, but the reason we conclude it's extraterrestrial is because there's no explanation of the phenomenon of all these sightings," Gravel said. He bemoaned "the American government keeping this information from the American public and the people of the world. … There's no question that there's something going on that's not explainable."

At one point during the "hearing," Kilpatrick appeared to buy into theories of extraterrestrial life.

"What you all have unveiled is there's something out there, we're not alone," Kilpatrick said.

The Wednesday morning session, attended by 55 or 60 in a dim auditorium at the Press Club in downtown Washington, D.C., will be featured in an upcoming documentary being produced by Paradigm, the same group that arranged the event. According to organizer Stephen Bassett, who founded Paradigm in 1996 as a political-advocacy and lobbying group to pressure the government to release information on UFOs, the whole event will wind up costing $600,000. Funding was supplied by a wealthy Canadian donor named Thomas Clearwater, Bassett told ABC News.

"Congress is out of the game. Let me tell you, the president is out of the game," Bassett told ABC News. "It is run within the military-intelligence community."