The staggering true story of a convicted murderer who demanded his own execution after 20 years on death row, David Sington’s engrossing documentary “The Fear of 13” arrives at Rome’s MIA fresh from its world premiere at the London Film Festival, ahead of its international and North American premieres at CPH:DOX and DOC NYC next month. In the vein of such recent breakout documentary hits as “The Impostor” and “Searching for Sugar Man,” Sington’s film tells a factual story with the dramatic beats of a fiction film, using an unorthodox yet gripping narrative style that is sure to help it stand out in the upcoming awards season.

It’s hard to go deeply into the film’s appeal without giving away its secrets; suffice to say, the story rests solely on the shoulders of charismatic protagonist Nick, who talks us through the shocking chain of events that brought him the death penalty in 1982, at age 20, in Pennsylvania. Speaking to Variety from the offices of the film’s international sales agent Dogwoof, Sington, who helmed 2007 Sundance Audience Award winner “In the Shadow of the Moon,” explained the various creative choices that make his film so distinctive.

Variety: How did you come across this story?

David Sington: It was my colleague, Christopher Riley, who brought the story to us. He had heard a radio interview with Nick on the BBC and he was very struck by the way he talked.

Variety: What attracted you to the story?

Sington: I think what attracted me about the story was not the issue of guilt or innocence, or even the death penalty, but the fact that that was somebody who had transformed their life by reading – and learning by reading – all the master storytellers, from Homer to Dashiell Hammett and Elmore Leonard, and by doing that had learned somehow to tell (his) own story in an incredibly eloquent and compelling way. Of course, as a filmmaker and a storyteller, this is what you’re striving to do yourself, and here you have someone who’s become a master storyteller, sitting in a prison cell reading thousands of books. That, to me, was the essence of the story. That’s why it’s called “The Fear of 13” — there’s a line that Nick came out with that summarizes his mastery of language. He knows all these strange words – like “triskaidekaphobia,” literally the fear of the number 13 – and knows how to use them.

Variety: What was the first step?

Sington: First of all we said, “OK, we’re going to need to interview this person,” so we got his agreement to do that. The next step was to research the story as fully as we could, which took a few months. In the end, we did two different two-day sessions. We went through the story and filmed about 12 hour’s worth of material over two days, and it was very, very emotional. It was absolutely compelling, but it was almost too emotional at times, so I said to Nick, “I think we might want to do this again.” So we did.

Variety: What did you do differently to tell these story?

Sington: In the film, there are four songs that are important to Nick’s story. In the first interview Nick talked about a number of songs, not just those four. So when we did the second interview we played him those songs. That way, we were able to get the story with a different emotional register, and after that we had about 22 hours of material to work with.

Variety: It’s unusual in that there are no other interviewees. Did you always intend that to be the case?

Sington:  I had assumed when I started out that I was going to do a more conventional film, where I would interview other participants in the story and build it up in the usual way. But having got this material, I wasn’t sure that any interviews would stand up against it. When you’re with Nick, you’re not going to want to cut to somebody else, unless they’re absolutely fantastic – and they’re not going to be as good as Nick. So then the question began: “Can we do it as a monologue?” Once we’d made the decision that we wanted to try that, we really had to prove to ourselves that we could sustain a film at 90 minutes with just one guy talking.

Variety: How were you funding the project at this point?

Sington: We’d spent quite a lot of money filming the interviews and we’d run out of our own resources to put into it. So this is where Robert Sternberg came in. Chris Riley found him. He’s not a professional editor, he’s a filmmaker and he teaches film at Imperial College, London, where he spends some of his time editing his students’ films. He was willing to spend his spare time working on it. We worked with him for about two and a half years, and in that time he ended up doing about 10 weeks of editing. So we produced a version of the film that was literally just a monologue. Once we’d got that, it wasn’t difficult to raise the money we needed to finish the film.

Variety: How long did the whole process take?

Sington: An embarrassingly long time. It basically took eight years, and the reason it took so long was partly because of the business of doing things in our spare time but also because we went down a two-year rabbit hole. At one point we thought it might be interesting to try it as an animated film, so we teamed up with an animation studio and they did a five-minute taster. It was very effective, but it became apparent – to me, anyway – that we would never raise the money we needed to make the whole film like that.

Variety: The non-interview sequences are very impressionistic. How did you determine the style of the film?

Sington: Having raised the money to shoot the material that was going to be filling the blanks turned out to be quite a complicated thing to do. When you’re a documentary filmmaker you learn that, if you’re writing narration, that shouldn’t write a script that just tells you what the audience can see from the images. And I had the reverse problem: Nick paints such vivid word pictures that you can’t just merely illustrate them. I had to find a way of going at it slightly obliquely. I wanted to keep us in the cell with Nick, so I didn’t want to have scenes, as such, just images. Because my idea was that these are the images that come into his mind as he’s talking, which isn’t necessarily what he’s saying.

Variety: It’s also non-linear, which helps to build suspense. Was that always your plan?

Sington: The first question was, “Have we got enough material from Nick to tell it as a monologue?” So the first thing I said to Robert was, “Well, let’s organize it chronologically.” We did that, and we showed it to a few people. The reaction was very positive, and then I showed it to (producer) John Battsek, and he said, “Well, by the end I was totally riveted, but I have to say, I found it a bit difficult to get into. It really comes alive when he gets to prison.” It was disappointing, but of course John has won two Oscars, so you have to take him seriously. The next day I was having a shower, and in the course of the shower I worked out the structure. Ultimately, the film is constructed as a series of puzzles: who is this man, what did he do, why is it called “The Fear of 13,” what’s the significance of these images…? And as you go through the film, those questions are answered.