"Dennis" turned out later to be a man named Bob Lazar, who claimed he worked at a secret facility built into a mountainside just south of Area 51's main facilities.
The story started a UFO stampede that continues to this day. Lazar has tried to put the UFO tales behind him, and has been discredited in the eyes of some critics, but it is a story that simply won't go away.
The I-Team's George Knapp coaxed Lazar into talking about the last quarter century of UFO craziness.
The story that Bob Lazar told 25 years ago this week has gone around the world many times over, inspiring books and TV shows, and movies. Who knew that Indiana Jones' warehouse is out at Area 51?
Another repository of Area 51 lore is the exhibit at the Atomic Testing Museum. While in town recently for the interview, Lazar took the tour. He watched tapes of the first interviews he ever gave about his time working at S-4 and plowed through boxes of paperwork about his claims. Lazar re-iterated his preference that people don't believe his story.
"Look, I'm not out there giving UFO lectures, producing tapes. This is not a business of mine. I am trying to run a scientific business, and if I'm the UFO guy, it makes it really difficult, it is to my benefit that people don't believe the story," Lazar said.
These days, Lazar and his wife operate a scientific supply firm in Michigan. He has received media coverage because of the odd stuff he sells online but not everyone has made the connection to Area 51 and the stampede he started back in 1989, when he told of working at S-4 south of Area 51, where he saw flying saucers so advanced they had to be from somewhere else.
This is a model of the reactor that he says was able to generate its own gravitational field, powered by what he called element 115.
"Barry turned on the reactor, which is a flat plate, half a basketball essentially on it, just a hemisphere. And once activated you could not touch the sphere. You put your hand on it, just like poles of a magnet. The exact same type of force. We had a little golf ball and threw it at it and rebounded and knocked a ceiling tile out of place. That alone is something amazing that could change everything we know today," Lazar said.
The story exploded among UFO researchers, and just as quickly, led to questions and denouncements. The I-Team confirmed that Lazar previously worked at Los Alamos National Laboratory, but the I-Team also reported that his claimed education credentials could not be proven.
UFO experts including physicist Stanton Friedman also dug into his background.
"Here is a bright guy. I did a lot of checking. I find a lot of things didn't check out. It doesn't mean I disagree with everything he ever said, or that he was a liar all the time. It means I can't find the story as presented. What he did out there I don't know," Friedman said.
Lazar says there is no end to the questions, and even if he could prove he worked at S-4, someone would say he could have been the janitor, so he generally avoids the topic altogether.
"You want some of the fame? The fame. There is no big dump truck dropping off money at my house every Thursday night. I have better things to do. Generally, people have to twist my arm to come out and do things like that, as you know, you're the arm twister," Lazar said.
Those who were around him at the time the story broke, or took trips into the desert to see the craft fly above S-4 say, you really had to be there.
"There is a MUFON (Mutual UFO Network) moron that calls me every once in awhile and he says, 'you don't still believe that guy do you?' And I say, 'I lived it.' The whole two years, and it was fantastic, one of the greatest times of my life," aviator John Lear said.
"He wouldn't go to the trouble to make up a story to lie to the people and then perpetuate that lie. Bob has no idea who won the Super Bowl last year, or the World Series. He is just busy doing scientific stuff in the Bob Lazar world. He wouldn't waste his time perpetuating a lie on anyone," friend of Lazar, Gene Huff said.
"Look, I know what happened is true. There is no doubt. Period," Lazar said.
Lazar was known to have unconventional interests and a spotty financial record. So why would a top secret program let him in? One theory is that maybe someone predicted he would spill the beans, and was chosen because they wanted the UFO story to be planted. Lazar told the I-Team he can't rule that out entirely.
NOTE: The Area 51 exhibit at the Atomic Testing Museum is having a grand re-opening on Saturday, May 17. It is located at 755 E. Flamingo Rd. The phone number is (702)794-5151 and it is open on Saturday from 10 a.m. to 5 p.m. and on Sunday from noon to 5 p.m.