20/20's the big lie returns. Now with matt gutman. Reporter: In these cynical times when heroes are scarce, navy s.E.A.L.S. May be the one thing americans can still believe in. Capable of almost superhuman feats of combat skill and endurance, they are the real deal. Famed for taking out world enemy one osama bin laden. Hollywood has turned the s.E.A.L.S. Real life exploits into big budget movies, like the just released flick "lone survivor." So if you ever happen to meet a seal, you might react the way carol roberts did when she met aj dicken, with awe. Your first impression of him? He's a big guy. He commands authority by his size. Reporter: It was 2011 in carson city, nevada. Carol, herself a navy vet was a student at dicken's military-style self defense school. That's dicken, running and gunning in videos he made to promote his business. It looked like, you know, a lot of fun. Reporter: Learning from a navy seal was part of the fun. But dicken wasn't just any old s.E.A.L. He claimed tours of duty in vietnam, desert storm, you name it. Earning him the status as most decorated navy seal in history! If anyone asked for proof, he had his discharge papers at the ready. Even emails om colonel oliver north. Dicken's self-defense school was a success. But he dreamed way bigger, he wanted to set up his own lucrative overseas security business. To bankroll his new venture, dicken turned to a pair of local doctors enrolled in his self defense classes. The savvy seal talked them into investing upwards of $850,000. He said, 'i'm ex-navy seal, then I went into the cia he can be very charming, very engaging he presents a face that kind of draws you in. Reporter: Dicken's mystique and the allure of a big payout, led carol roberts to sign on as marketing director of the new firm. They needed somebody to do their marketing and so I said, "i'll do it." Reporter: You actually quit a good job in order to work with dicken? Cause you thought the money was coming in. Yep, because I had seen the contracts. Worth hundreds of millions of dollars. Reporter: Yep, dicken, the sweet-talking seal, had landed a security contract with a united nations' affiliated organization, allegedly worth about half a billion dollars. It's all coming together. A.J. Dicken's excellent ground. All of a sudden it was like, we're leaving for burundi in a week. Reporter: No, this isnt the script for an action flick. But the first bit of business for dicken's new venture. Deep in the african nation of burundi, there's a construction project looking to hire a security firm. Dicken leads an expedition there to "seal" the deal. Carol roberts is part of the team, as is chief pilot mike reynolds. But shortly after they land, the wheels start falling off. By the second day, we realized that people didn't know who we were, what we were doin' there. His house of cards started to crumble. The business trip to burundi has turned into a bungle in the jungle. And when the going gets tough, the tough get drunk. He'd fill up a glass of vodka and have that down for breakfast. I mean, the stuff he was comin' up with is just, it was insane. The whole situation there was just dangerous. Reporter: Carol's suspicion grows when the power goes out in the hotel and the supposedly steely-nerved seal nearly wets his fatigues. He freaked out, picked up his phone, runs into the other room talking to the c.I.A. To have them reposition his satellite so he can make sure that the rebels aren't coming to get him. Reporter: Just then, a friend back in the states tips carol and the team off to a strange video, just posted on youtube. If I get another call asking if aj dicken is a navy seal, I'm gonna pull this pin out of the grenade and blow myself up. Reporter: The guy in the video isn't some lunatic, he's actually a real former navy seal. One senior chief, don shipley. I knew right away he was a fake, and all I gotta do is check your name. I'll check your name, a couple of keystrokes. I can tell you if that guy's a seal or not. Reporter: Shipley has made it his personal mission to ferret out the fakes. Every single day, using a special database only real s.E.A.L.S. Can access. How many guys have kpu posed? Thousands. I verify, on average, at least 20 fraudulent seal claims every day. Reporter: But shipley says aj dicken was no ordinary seal faker. For one thing, his claims were so over the top. Remember those discharge papers? The awards in here are outrageous. Why are they outrageous? Oh, he says he has got two medals of honor. That hasn't happened since world war i. Reporter: In fact, dicken never served a day in the military. And his phony resume was also missing a key detail. A burglary conviction that landed him in a california prison. For the team back in burundi, the last bit of dicken's cover's blown to bits. But knowing he's a fraud is cold comfort. You're sitting in the middle of africa with somebody that you're pretty convinced at this point is a sociopath at best, a psychopath at worst. Reporter: The team hightails it back to nevada, and carol roberts wastes no time blowing the whistle about the real a.J. Dicken. I went to one of the doctors with all of the evidence I had and said, "you have a problem." Reporter: Dicken was fired. And escapes time. Leaving only burned bridges and emptied wallets. Months later, dicken's back on the radar when abc station kgo picks up his trail, leading to his parents' house outside los angeles. Aj, I need to talk to you about your navy seal background. I don't have a navy seal background. You told a lot of people that, didn't you? No, I did not. Reporter: Now, true to form, dicken heads for the hills, again. But nobody is sure which hills, until a few months ago. We've been trying to track down dicken for weeks. We know where he is. 20/20" tracked dicken to a secluded property in rural arkansas, where the road ends. The man doesn't get out much anymore, but we finally spotted him. Mr. Dicken? I have nothing to say to you. These appear to be your discharge papers and folks in the navy seal community say you're not a commando, you're a con artist. I have nothing to say. Reporter: If you talk to me I'd like to hear your side of the story, sir. Reporter: But dicken can't drive away so easily from his shady past. He's an ex-con, still banned from handling weapons, meaning this rambo routine is illegal. And now he's facing felony firearms charges in nevada. But as of today, a.J. Dicken still walks the earth. Maybe not as a seal, but as a free man. The people who say he's conned them, are hoping to see him soon -- wearing a different kind of uniform. You'll never get paid back for what you lost. But can you ever get payback? To be able to bring this to light and not just sweep it under the rug, is what my payback's gonna be. And that's all he has been, and that's all he ever will be.