Documentarian Alex Gibney, whose last film Taxi to the Dark Side was an Oscar winner about US army torture practices in Guantanamo Bay, Afghanistan and Iraq, returns to screens this week with a new feature about the life and times of Hunter S. Thompson. The noted but controversial journalist, who pioneered the Gonzo movement, died in 2005. He wrote the book that became the film Fear and Loathing in Las Vegas, and the movie's star, Johnny Depp, narrates passages from Thompson's writing in the documentary. RT caught up with Gibney to learn more about the movie.

Was there any hesitation from you about trying to explore the mind of a guy like this?

Alex Gibney: Not really. One of the things I thought I could do that hadn't been done -- or at least hadn't been done in a long time -- is explore the work. That's why I put Hunter at the center -- he narrates the film himself. We put together a number of his words so that they would form a kind of narrative. That was important because he was this wild and crazy guy who was a drug-taking action hero, but I think we wouldn't really care about him unless he'd been a really great writer.

How much did you know of him beforehand? Did you have a chance to meet him?

AG: I never met Hunter but I certainly knew of him and knew a lot of people who knew him. And I certainly knew the legend. What's that line from The Man Who Shot Liberty Vallance? "When you have the truth and the legend, print the legend." I had fun printing the truth and the legend, I think. I came from the outside so I had an advantage in some ways. I wasn't allied with anybody, or part of any clique, so I could come in and ask a lot of questions and just say, "Tell me about him." I found out a lot of stuff that I didn't know.

Is that part of the joy of being a documentarian; that you have the opportunity to explore?

AG: Yeah, you get paid to learn -- how good is that? I feel lucky in that sense -- you wade into someone's life and you get to learn a lot of stuff that you didn't know before; that's exciting. There's something wonderful about the contradictions of everyday life that's impossible to resist. I started out as a fiction filmmaker and may do some fiction films yet in the future, but I also see a lot of fiction films which look beautiful but seem dead. They don't have that weird, quirky vitality that the best documentaries have. There's something about that which I really like.

Do you ever worry that you won't be able to come out of the other side though? That the story you're discovering doesn't have an end?

AG: I do, I always worry about structure and the end point. I haven't a clue what the structure is going to be when I go in and it's a terrible feeling. But if there's one thing I've learned over time it's that it will come. I think there's always enough interesting about almost any subject that if you get stuck you can just take a turn into a different direction. There's always something there, it just takes time to find it and then come back and structure it in a way so that it becomes a story. Even though I love documentaries, there are a lot whose structure is just too aimless for me -- I like to construct documentaries in the cutting room so that they feel like movies and they have that sense of momentum.

Presumably you can be a little less conventional when you're working on a documentary about someone like Hunter.

AG: I think the whole life of Hunter S. Thompson, and his art, is "don't be afraid to mess around." Gonzo journalism is gonzo. The name comes from a Hammond organ tune from James Booker and it's just got a weird, funky vibe that's wacky. You never know quite what to expect from the song. That's the way Hunter's writing was and that's what I hope comes across in the film, too.

As familiar as Fear and Loathing is, the film is the most interesting when it's sharing the lesser known details of Hunter's life.

AG: Right, it was fun to really dig at the stuff that I didn't know much about. The letters are fantastic and we included some bits and pieces from manuscripts that are yet to be published, including a full book he wrote on the NRA. In the book, Hunter ends up being too intense for the National Rifle Association. He terrified them because he walked into the offices with a gun and started shooting things and they were like, "No! Anything but guns!"

What surprised you most about him?

AG: I think what surprised me most was learning from people who knew him that he had very high highs and very low lows. He had a manic side but he also had a cruel and vicious side. That's, I think, one of the reasons he was so good at championing and chronicling the American character, which is so deeply contradictory between this great sense of idealism and possibility and this dark, brooding violent streak -- what Hunter called fear and loathing. That was interesting to me, there was something in his personality that may have allowed him to channel the larger character of the American character.