Transcript for Meet NYC Man Who Commandeers Subway Trains, Buses

Tonight you're going to meet a man whose life has been ruined by his own obsessive urges. Diagnosed with asperger's he says he's plagued by unyielding desire to drive public trains and buses. So much so that when he sees one of them he says he can't stop himself from hopping aboard and driving away. He's been jailed over and over again but he says he's never been given treatment, so does he need punishment or help? Here's ABC's John donvan. Reporter: The trains of the New York City subway. Rumbling. Screeching. Moving nearly 6 million riders a day. And also triggering something in a man named Darius Mccullum. A compulsion. In a way, a love that has ruined his life. A Manhattan man is getting a free ride to prison. He started hijacking modes of city transportation before I was even born. There's a man that really likes trains a lot. Police have just caught a guy for the 23rd time trying to pose as an mta worker. A notorious New York City public transit bandit. Mccullum's is a unique and troubled New York story. Reporter: Perhaps you remember hearing years ago about a 15-year-old New York boy arrested for sneaking into the driver's cab of a subway train and taking it for a ride. Good morning, passengers. The dynamite D train next stop -- please step up carefully and next stop will be sixth avenue -- Reporter: It seemed amazing he knew how to handle controls, kept the train on schedule, announcing every stop, letting passengers on and off. News 4 New York. Officials were stunned to say the least when they heard a 15-year-old queens boy had hijacked a subway train and taken it for a joyride, stopped at stations, let some passengers get on and off, had a fine time. Reporter: This kid needs to get some counseling. But obviously he wasn't trying to hurt anybody. So whatever happened to that kid? It's a downpour here. As we make our way towards Riker's island, New York City's jail, I'm going to see Darius Mccullum for the first time in at least three years. He was in jail. He got out. And now he's back in jail. Reporter: Riker's island. New York's notorious jail. There's our man. Sorry to see you back here. I was sorry too. Reporter: Diagnosed as an adult with asperger's syndrome, most often described as a form of autism. I met him the first time while interviewing him for one of the stories told in my book "In a different key: The story of autism." It's the trains that bring him here. His whole life, it's been the trains. Why does this keep happening? It keeps happening because I can't seem to have my urges and impulses under control. Reporter: At first when Darius was a teenager he was handed the controls and taught the skill busy trainmen whom he had befriended and took advantage of his interest so they could take breaks. Their irresponsible behavior helped convince the young boy he was doing nothing wrong. I ran away to the subway system because I felt protected down there. My safe haven, my sanctuary. Reporter: That was then. Now as a 51-year-old, Darius has been arrested 32 times and has taken control of New York City trains and some buses too more than 100 times. It is all for the same basic repeat offense. I'm really good with trains. But I can't seem to figure out people. Reporter: That's Darius speaking in a new film, a documentary on his life and his obsession called "Off the rails." Its director is Adam Irving. Darius Mccullum has spent more than half his life in prison for impersonating new York City transit workers. He has asperger's. I thought, there's a story. Reporter: Irving posits Darius' compulsion to be part of the subway system literally results from his having asperger's syndrome, often thought of as a form of autism. People on the spectrum, they like routine, they like rituals, they like schedules. And trains run on a schedule. When he's in that world of the subway, there is a kind of sense where, everything is going to be okay there. Like he's kind of ended up in wonder land. Reporter: Or put another way, when I asked Darius about a scene in the film where he's donning the uniform of a transit police officer from his own collection -- Everything about the uniform has to match from head to toe. I guess I felt like maybe Batman. Batman? Batman. What does Batman do? He doesn't have the powers like Superman or ice man or other people, he's just a regular man. Batman always seemed to do good for people, and I felt that I did good for people too. Reporter: Yet even though Darius knew he was breaking the law and was risking jail time every time he offended, he just could not stop himself. In those moments when you give in to the obsession and take a train, by take it I mean steal it, are you aware that you're doing something wrong? That this is wrong what you're doing? At the time I'm doing it, no. Because I feel like as if I -- I'm doing the right thing. It feels right to you? Maybe that's part of the issue of what I'm going through. What feels right to me may feel wrong to somebody else. He can't help it. Sort of like the addict who might have been clean for X amount of time, and one day that drug or that drink is in front of them, and guess what, they're like not caring about tomorrow. The need for that drink is powerful. For the record, has Darius ever hurt anybody with his train obsession? No. Darius has never hurt anyone through his impersonations of transit workers or taking transit vehicles. Also, for the record, has he ever committed any other crimes outside of this? No, not to my knowledge or according to his rap sheet. Reporter: But here's what else has never happened. In none of the correctional facilities he's been sent to was Darius ever provided any sort of meaningful therapy to help control his behavior. You do want psychological treatme treatment? Yes, I do. If you could get treatment what would you want it to do for you? Where would you want it to get you? I would want it to get me to try to understand what's really going on with me. I would want it to get me to try to help me overcome what I'm actually going through. How to resist not wanting to take a bus, take a train, anything hike that. Reporter: Which may be just one reason that his periods on parole are always so short-lived. He was actually applying for jobs. He ran out of money and he didn't want to tell us. And he was going to be homeless on the night that this happened. That's where he really has difficulties when he gets scared. Any person facing homelessness, with not a dime in their pocket, is going to be scared. This is not necessary. We can do something about this as a society, rather than lock people up and throw the key away. Reporter: One might wonder why doesn't the transit system just give Darius a job? He knows its inner workings so well and obviously he cares about its performance. But apparently no one wants to risk hiring an ex-con and have something go wrong. I think if there's a quiet place in the country where Darius can ride trains or work in a transit museum, I think that would make him happy and make a lot of people happy. We just need someone to step up to the plate and say, I like this guy, I'm going to hire him. Reporter: Right now Darius faces charges related to the unauthorized driving of a city bus. He could get more years behind bars. His diagnosis of asperger's has not bought him much sympathy from judges in the past. The pity is Darius comes across as a good guy. Maybe you'll see that if you happen to catch "Off the rails." That's one reason Darius himself wanted this documentary made. I want this documentary not only to help me, to help other people. Maybe I can use it in the courts in reference to my case. Maybe they could say, wait a minute, maybe we're taking the wrong approach, maybe we could do something different. Reporter: Maybe. But that depends on whether he gets the chance to try one more time. John donvan, ABC news, New York.

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