Transcript for The wild life of John McAfee, mysterious cybersecurity pioneer
He's the elusive and eccentric millionaire behind the household name that's protected millions of computers for decades. But after John Mcafee cashed in on his pioneering anti-virus software, he dropped off the radar. He became an international fugitive, running from police who wanted to question him about a murder in Belize. And now he's finally ready to tell his story, but only and exclusively to ABC's Matt Gutman. Reporter: He is a party animal. John? Huh? Reporter: A one-time tech multimillionaire. It is the number one computer threat. Reporter: Presidential candidate. Stand with me to protect our freedom. Reporter: And international fugitive. John. We begin with that software millionaire on the run suspected of murder. Reporter: John Mcafee became rich and famous for creating and selling his self-named anti-virus software. You made $100 million from selling Mcafee, right? That's what they say. How much did you make? Much more. What did you do with the money? I wasted it like everybody who has money. Reporter: He built nine homes, filled them with expensive art and furniture, bought a fleet of antique cars. Is that love? Isn't it selfishness? Reporter: Even creating a zen yoga retreat. But Mcafee says his zen was disturbed by a constant wave of what he calls frivolous lawsuits. So he decamped to this idyllic-looking compound in Belize. John. Mcafee. Has been eluding police. Reporter: But trouble still followed him. In 2012 authorities in Belize named him as the sole person of interest in the murder of Greg fall, his American neighbor who was shot in the head inside his home. They sought Mcafee for questioning. Mcafee refused, instead going on the run. Of course he's the main suspect I hear. You've got the motive. You've got this incident with the dog. Reporter: Mcafee dodged authorities all the way back to the U.S., where he has been ever since, never charged with a crime. Now for the first time he is sitting down to answer questions in a no-holds-barred interview. Why did you go on the run? Because if I didn't go on the run I'd Abe dead man now. Reporter: I first cross theed paths with Mcafee in 2012. . From just outside John Mcafee's compound, its owner this morning is on the run. Reporter: That was when he was hiding out from authorities and would only talk to me by phone. When we say we're going to talk tomorrow, does that mean face to face? Reporter: After three weeks in the jungle in Belize he fled for Guatemala, where he was arrested. It was all caught on camera by vice TV. Once in jail he faked a heart attack and was rushed to the hospital, followed by the press. Miraculously, Mcafee opened his eyes and asked the nurses not to undress him in front of the media. Not in front of the press, please. You faked the heart attack. Sure I faked it. What would you have done? Reporter: He was deported back to America, landing in Miami, where he met his future wife Janice. She was a prostitute at the time. He saw the human in me. He thought I was worthy enough of a second chance. Is it strange for you to have found love in your late 60s, early 70s? I instantly saw in Janice what I had been looking for my entire life. Reporter: The two of them live in this upscale but hardly lavish spread. They share their home with their ever-present bodyguard and an arsenal of guns. Is it a real gun? It's a Real gun. Do you have a fascination with guns? I have a fascination with survival. Reporter: And then there is this pack of dogs. Back in his Belize compound Mcafee had a swarm of dogs there as well, which was a bone of contention for his neighbor, Greg fall. Greg's mother, Eileen Keeny, says her son wanted a peaceful retirement in the caribbean but she says it was anything but peaceful. Now, Greg would be walking past mcaknee's house, and there's going to be dogs there. They're usually fenced up, but he says I just want to warn you. Reporter: She says those dogs were aggressive. Fall allegedly told friends that he was going to take care of the problem himself. Greg had told him that he was going to poison the dogs. Reporter: Then one evening some poisoned meet was thrown over Mcafee's fence. All nine of his dogs were poisoned. The very next night an intruder snuck into fall's home, tased him several times, and then shot him in the head. The house showed no sign of forced entry. Nothing was taken from inside. He was brutally murdered. And he had no enemies. Reporter: The case is still open. And Nanette burrstein's recent documentary "Bringo" alleges that Mcafee was the mastermind behind fall's murder. You think you found the smoke to the fire of the Greg fall murder. Yes, I did. Reporter: In "Bringo" this man Mcafee's beachfront caretaker named Cashen alleges his boss paid to have it done. The following morning sometime around 9:00 John called me. He said take this money, $5,000, and go put it in this guy's account. Reporter: Cashen says the man who got that money called him late the night of the murder to come pick him up. Then I realized that this $5,000 was for him to do that. To do what? To kill the guy. Nanette has been after me since -- Reporter: In a video Mcafee posted online Cashen would later recant his story. John had nothing to do -- Let me make this perfectly clear. I had nothing to do with the murder of Gregory fall. You're asking the most ridiculous thing. You have to admit that it's not ridiculous. It is. That your dogs, nine of your dogs, your beloved dogs were poisoned -- Were killed by the government. That would make a man who loves animals absolutely irate. Right. It would be enough to make a man who loves his dogs willing to kill someone. Does this man look to you like he would be stupid enough to kill whoever was responsible -- I don't think he would be -- did you order a hit on him? Of course not. Please. I am sick of Belize. I'm finished with Belize. That's your choice. I have a couple more questions about Belize. As we ratcheted up the pressure on Mcafee about Belize, he started to walk out on our main interview. You're walking out on this. Yes because you have not kept your Word. I have kept my word. Reporter: There had been month preconditions to the interview and Mcafee quickly calmed down and sat down. You're computers are no longer back home in the office. They are in our hands. Reporter: These days Mcafee could be called a prophet of digital doom and his apocalyptic warnings about today's cyber threats attract plenty of eyeballs both in person and on TV. We're being spied on by our government. John Mcafee -- Reporter: He's now the CEO of mgt capital, a company that invests in cyber security companies like the one that developed this cell phone which Mcafee claims is the first ever that can't be hacked. Given the obsession with hacking, it seems like the perfect time for John Mcafee. Well, it's an opportunity for me to speak again. Police are listening. Reporter: And truth is it's one of the reasons he said he agreed to spend time with me. What do you hope to get out of this interview? I hope to get at least ten minutes that I can talk about the serious problem in the world, which is cybersecurity. We're living in 1984. Our freedoms are being restricted. Our security is being eroded. And we have no more privacy. If we lose privacy, we will lose civilization and we will certainly lose our humanity. Reporter: With Mcafee the truth is always slippery. You could say there's only one constant in his life. How would you define yourself? Are you a madman? Are you paranoid? Are you an entrepreneur? Who are you? All of the above. I've always followed my own path. The drummer that leads me is an odd drummer. But I follow the sound. Reporter: For "Nightline" I'm Matt Gutman in Lexington, Tennessee.
This transcript has been automatically generated and may not be 100% accurate.