Now let's pay a visit to a made man with some hot wheels. Reporter: This is a story about a murder. The murder of a popular atlanta rapper called lil phat. And about a fascination with a russian... See More
Now let's pay a visit to a made man with some hot wheels. Reporter: This is a story about a murder. The murder of a popular atlanta rapper called lil phat. And about a fascination with a russian mobster turned russian informant. Mani chulpayev accused in the murder of lil phat, something he strongly denies. There is no reason to be afraid of me. I'm the nicest guy you'll ever meet. Reporter: And dante jackson, now under investigation by the fbi itself after allegations he obstructed the murder case while receiving extravagant gifts from his informant. It's nice to have an fbi agent that is looking over your shoulder, I guess. Reporter: Our abc news investigation into all this began months ago in fort lauder daily where a party van cruising down a 1 a chose to fit in. That's why we used it to get footage of chulpayev, a 35-year-old soviet immigrant who we were told was involved in a huge criminal operation, a man with a well documented record of ruthless violence as a russian mafia boss in new york. Beat up people, threatening, extorting, kidnapping, mugging, torturing people. Reporter: THIS LAWYER CAM To know him well when he cross-examined him about his crimes. How bad was he? On a scale of one to ten, probably 100, pimping women and threatening to kill their families if they didn't work as prostitutes. You name the crime he did it. Reporter: For all his convictions he could be deported to russia but he's not. He's living a fancy life in florida, one day in a ferrari, a silver mercedes, a range rover, thanks to federal prosecutors who have protected him and kept him on the street as an informant and government witness. He's very smart, managed to play the system for years and years. I need these people out of HERE. Reporter: As we found when we first approached him, mani chulpayev is not someone who likes to be challenged. We're from abc news. I don't care where you're from. Get the out of here. You know the allegations you're up against? I don't care. He hasn't changed much. Same arrogance, tough guy. Reporter: Just a few weeks later we saw the other side of chulpayev as he invited us for a spin around town in a bla maserati and a spin on what an honest fellow he has become. My father thought I would be a nice jewish boy, I don't know. He had hopes. Amidst almost $2 million of luxury cars, including a half million rolls-royce, that protected under the fbi he had returned to his criminal ways. How can we rely on what you are saying? Because I stand behind what i say. You have lied a lot. To the government, yes. Were you a thug? No. I was just not afraid. That's two different things. Chulpayev came to the united states as a 12-year-old. 16-year-old I had my first mercedes benefits. I went to school to show off. He became a major organized crime terror in new york, ultimately making millions of dollars. What have you been convicted of? I was convicted of, you know, running a -- being in an organized crime group back in the days. Arson? Arson. Kidnapping? Kidnapping. Extortion? Conspiracy to call that. Reporter: Convicted as one of the men behind the arson that destroyed this supermarket. But to avoid a long prison term or deportation, chulpayev quickly made a deal to cooperate with the government and the fbi and rat out his partners in crime. You were convicted of crimes that could have put you in prison for life? Yes. Could have led to your deportation? Yes. None of that happened. Of course because i cooperated. You took the fbi's way out? My way out, yes. Reporter: At the time the fbi and prosecutors said chulpayev was one of the most important witnesses ever against the russian mob. Now despite his tattoo, the inform ability says he does have one regret. Given your background did it bother you to be known as a snitch, a rat? Of course. It still bothers me to this day. But it worked. After his testimony he was set free, moved to atlanta and promised protection by the fbi. That was 2002. Who was the atlanta man hiding these stolen cars? Reporter: Just three years later chulpayev was back to his criminal ways, caught in a luxury stolen car ring operating in georgia, south carolina and ohio. Chulpayev was arrested, convicted but served less than three years because he agreed to testify against others in the stolen car ring. How many strikes do you think you deserve? One strike. You got one strike and a second strike. So I got lucky. Reporter: That was 2005. Fast forward to this year and again allegations it's the same old story with chulpayev, back to his criminal ways, selling stolen cars and course, he was still being protected by the government. He's untouchable. Reporter: One of the many alleged victims we heard about, travis jones and his wife elizabeth sayihulpayev cheated them by selling them a stole encar. He was briefly cain into custody for driving a stolen car but he's out the $10,000 cash he gave chulpayev. But when jones filed a police report in his hometown, he was told by local police that their hands were tied, that the fbi was protecting chulpayev. They told me that he is involved with other agencies and that they're using him right now and that he can't be arrested. He's being protected? Correct. I want to talk to you about some of your car deals, sir? No comment. Reporter: In fact with the abc station in atlanta did a story about chulpayev and the alleged stolen car ring earlier this year, reporter jim strickland says he got an unusual call from the fbi in atlanta just a half-hour aafter this confrontation with chulpayev at his business. I've been doing this 32 years, it's never happened before. It's got to tell you something. What? That mani was inter woven with the fbi in atlanta deeply enough s that he can make one phone call and they're instantly calling me to find out exactly what the story is. Reporter: It turns out that the story is that a criminal that the fbi twice helped keep out of prison is now accused of felony murder, something we learned only after this interview. You were a serious criminal connected to russian organized crime. You testified for the fbi. They put you back on the street and you broke the law again. That's the record. So what's the point? The point is you have criminal ways that don't seem to go away. That's not true. That's not true. I'm just smarter than you and that's it. Verage guy that thinks ahead. That's what it is. People can't stand that. Stupid people can't stand it. Smart people, they work with me.
This transcript has been automatically generated and may not be 100% accurate.