Paul Solet has long had the ability to take an unbelievable premise and find its underlying humanity, whether it was his 2006 debut “Grace” which tucked a cautionary tale about motherhood into the tale of a blood-craving baby or unearthing a tender drama about regret at the heart of an exploitation flick “Bullet Head” in which a group of thieves are locked in a warehouse with a killer canine, so perhaps the only thing that isn’t surprising about “Tread,” the director’s first foray into nonfiction, is all that he’s able to find beneath the surface of an extraordinary 2004 rampage in the small town of Granby, Colorado.

Just over a decade after a welder named Marvin Heemeyer rode roughshod over Granby with a bulldozer he redesigned into a makeshift tank better suited for combat, Solet heads to the wintry pocket of the west where the locals are still coming to terms with exactly what happened as a land dispute spilled over into violence. Heemeyer, an Air Force vet who was known for being aggressive when he was racing snowmobiles but little else, had found a deal on a parcel of land in the summer of 1992 at an auction of foreclosed property, outbidding Cody Docheff, the proprietor of a concrete company who had planned to build a plant in the area. While that much can be agreed upon, “Tread” attempts to hash out what happened after as Heemeyer grew increasingly volatile, whether provoked or not by Docheff and others in the tight-knit community, when his bid for the property got tied up with concerns about its sewage system and indeed, the shit piles up as the two sides fail to reach a compromise.

While the incident is truly unique in how Heemeyer carries out his revenge plot, “Tread” goes a long way towards articulating how violence has become such a common resort for the alienated in America and how frighteningly easy it is to organize under the radar. Through a seamless mix of interviews, recreations and chilling audio tapes Heemeyer recorded for himself just before going on the attack, Solet restores a sense of magnitude to an assault that somehow eluded national headlines and illustrates how it truly could happen anywhere. Shortly after the film’s premiere at SXSW, the director spoke about how he became aware of the incident in Granby, working in nonfiction after a career in narratives and being sensitive towards a community still reeling from the events of 15 years ago.

How did this come about?

I got an e-mail from my brother who’s been a prosecutor for many years, so he’s got a really good eye for true crime stories and he just sent me a link to some footage of the machine with a question like, “How has this not been made into a movie?” This is probably seven, eight years ago and I saw this thing and I was like immediately clear that there’s an incredible character study here, completely apart from a spectacle of just the imagery of this thing that’s out of a war zone, driving through small-town America with this procession of first responders totally helpless to do anything. It’s totally clear that this is someone who is mad as hell, organized and highly skilled as a craftsman, so there’s a conflict there that I just really felt compelled to understand more deeply.

Was this the kind of story where you could start at the end and work your way backwards in terms of figuring out the narrative structure?

I had done a lot of research and I had a relationship with one of our subjects, Patrick Brower, who was the editor of the local paper in Granby for 20 years and was in fact one of Heemeyer’s targets. Patrick had written a book, so I was quite familiar with the details of the narrative, but we kept it very malleable, like we knew we would be discovering more and more throughout. We did our first round of interviews, then we began editorial and then we began formulating the story and allowing those discoveries to happen and only at that point did we begin to start to chart out where recreation would be necessary. And we adjusted and readjusted as we learned more about what happened and why it might’ve happened.

To do the recreations, were you shooting in some of the real places in Granby?

No, we were very conscious of not retraumatizing the community. We talked to people on all sides of this conflict, whether it was Marvin’s close friends or his former girlfriend or the first responders that were tasked with stopping the machine or the people that he targeted, and moving back and forth between all of those parties, all on the same day, I had an overwhelming sympathy for all of them. It is a cautionary tale and it is tragic in many ways for all parties, so I just felt a lot for them. They really suffered a great deal and still do in many ways, so we would never recreate this there. We did the recreations in a community in California called Porterville that has a lot in common with Granby and had a similar enough look that we could represent it as such.

Were people actually reticent to talk about this?

We were very careful in approaching people and I sat down with people beforehand and my producers and I made sure that we understood that our primary interest was to empower the people of this community to tell their own story because one of the first things I realized when I started to research this was that there’s a ton of shit out there about Marvin Heemeyer, but almost none of it has been written without another agenda, and even less has been written by anyone that’s ever set foot in Granby. So it was very important to us to give them that platform.

I imagine you’ve done interviews for research on the narrative films you’ve made, but that’s on background. Is it different to do them to be part of a film?

It’s interesting. Of course, there are differences, but there are also a lot of similarities. Whether I’m working with the actors in “Bullet Head” or sitting with a subject, my job is really the same — it’s to provide for them a space for them that is really safe for them to find the truth, not for me to impose the truth upon them. [I need] to be present with them and to really listen to what they’re saying and what they may not be saying and to just ask questions. So in many ways, it turns out that they’re really strikingly similar and I loved talking to these people. I was so deep into the story by the time I met them, they really were like celebrities to me. I don’t really get starstruck but getting to see these people who had been through this real thing, it was really quite remarkable.

There are these chilling tapes that Marv recorded that give the film its backbone. How did you get your hands on them?

In the weeks leading up to the assault, Marvin made a decision to sit down and record two-and-a-half hours of audio tape to tell his story and discuss what he felt was motivating him and why he felt upset. When he was done, he put them in an envelope and he sent them to his brother right before the incident. Right after the incident, his brother turned them over to the FBI and the FBI turned them over to the Colorado investigators and the Colorado investigators turned it over to the press. Once it gets to the press, it’s public record, so it was actually quite easy for me to acquire the tapes.

There’s also this great aerial map you create that gives a sense of being there while creating the context around it, showing Marv’s property in relation to the encroaching concrete plant. How did you figure that out?

Yeah, I have an amazing graphics team and they actually did the title as well, a gentleman named Kook Ewo from Paris and he’s a real creative storyteller, a real artist and he and I had real conversations about how best to represent that. It’s important to me that nothing’s gratuitous or style for style’s sake anywhere in film, documentary or scripted — the goal is the truth and anyone who’s listened to Errol Morris talk for 25 minutes has heard similar things, [where] style does not equate to truth and I believe that. If we’re working responsibly and thoughtfully, we can create images that help the truth be more honestly and economically represented in a way that’s more readily metabolizable. In this case, one of the tertiary themes [of the film] is about land and barriers that’s in many ways, while not uniquely American, certainly quite American, so that was how the idea of the map and grafting the graphics onto that evolved.

What’s it like getting to the finish line?

It’s so awesome. I started work on this movie seven or eight years ago, so it’s really been with me for a long time and it’s meant a lot for me for a long time, so getting to premiere it at South By, which is just a badass film lover’s [haven], like unapologetically enthusiastic about great stories festival — that’s the place I want to be. It really is the perfect audience for us to share this movie with for the first time.

“Tread” will screen at SXSW on March 14th at the Alamo Lamar D at 11:30 pm and March 16th at the Paramount Theater at noon.