Recent years have seen a spate of films dealing with the Columbine school shooting in Colorado, from Michael Moore’s activist Oscar-winning documentary that used the incident as a jumping-off point for a diatribe about violence in America to Gus Van Sant’s haunting, hypnotic minimalist “Elephant.” Ben Coccio’s debut feature “Zero Day” may have been inspired by the same event, but it’s very different from either of those: framed as a mock documentary employing a video diary prepared by the perpetrators themselves, the film follows voluble Andre and deceptively laid-back Cal as they methodically prepare and carry out the onslaught against their classmates.

“It’s kind of nice to have something give you a structure beforehand and then work from it,” Coccio–who shot and edited the picture as well as directing it from a script by himself and his brother Chris (who also appears in it)–said in a recent interview. “When you’re doing something off a real event and you’re fictionalizing it, you have the total freedom to take artistic license, but you’re still obviously going to stick somewhat to the drama of that original event.”

But “Zero Hour” isn’t designed as a quasi-documentary account of the Columbine incident itself; its subject is a later, totally fictional episode, but one with eerie reminiscences of the Colorado tragedy. “I did a fair amount of research, not just about school shootings but I also researched Charles Whitmore and other events kind of similar to Columbine,” Coccio said. With respect to Columbine itself, “I tried to learn as much as I could about the specifics of what happened, and what the people going into it were like. There are some small specific things that are taken from Columbine”–the fact that one of the killers goes to the school prom shortly before the shooting, and a coda that shows vandals destroying memorials to the shooters, for example. “But I didn’t try to dwell on [that] too much,” he continued, “because my goal was always, when writing how this was going to unfold in the film…[to] say, ‘I’m a high school student in a post-Columbine world–how do I do it? What do I do, what do I tell my friends, what do I tell my family, what do I tell my partner, what do I tell myself?’ Thinking about it…was where a lot of the devices of the movie came from, primarily where I came up with the idea of doing the sort of ‘Blair Witch’ style thing…If people were going to do this, and they were concerned with the idea of scrutiny and of getting caught beforehand, it seemed like the perfect way [of proceeding]. There has to be a bragging outlet–that’s one of the main factors of doing this. And if the bragging outlet is this video camera that’s making a collective record of what they’re doing, then that says something more, too–because it’s not just a bragging outlet anymore; you’re also making a TV show or a media document. They’re media savvy, and I think that anyone in their position would be.”

That was part of the complexity of the two characters in the script. But there were other facets as well. “I wanted them to have this vision of themselves as somehow pure,” Coccio said. And they also had to have a convincingly juvenile side. “I thought that was essential. Apart from the movie having to have that just to be bearable, I thought it’s realistic and much more distressing. They’re humorous, they’re kidlike, at times they seem witty and intelligent–although it’s sort of an adolescent wit–and that’s all part of the tapestry. They’re not masterminds. They’re definitely not what they see themselves as. They’re not stupid, completely unaware of what they’re doing, but they’re not a higher-evolved being. They’re just kids…They’re approaching the project as adolescents would.” And he wanted to construct the film so that viewers would be uncertain about which of the plotters was really the leader: Andre seems the organizer, but very often Cal seems to be the driving force. “I’d love [viewers] to argue who’s in charge, so to speak,” he said.

But the mode of storytelling, Coccio explained, also had risks. “I knew if I was going to approach it in this fashion, if I didn’t make it seem authentic, it would fall apart,” he said. “That was part of my decision to use real kids in most of the roles, and their real families. I had written most every scene…but the intent was always to give [the performers] that and [have them] improvise based on it and say their own words and be as authentic as possible. One of the designs of the film was to get kids to be real and be themselves.”

The success of that, of course, depended on finding the right boys for the roles, and Coccio auditioned actual high school students from drama clubs and classes. “I never wanted the potential actors to know what the movie was about,” he recalled. “I had them do a few improvs and went from there.” What he knew was that he wanted “to have them physically different to play off their psychological differences and their character differences” and not to “fit anyone’s agenda as to what someone who might do something like this might look like. I didn’t want anyone who was too Gothed out or too punked out, or anything like that.” He was lucky to find Andre Keuck, a dark-haired, agitated type, and Calvin Robertson, a tall, lanky, laid-back blond. “They matched the characters so well,” he said, “and brought so much more to it.”

One of the special contributions the boys made was a scene in which Cal tells Andre to drive with his eyes closed, depending on his directions. “That to me is kind of a defining scene” in depicting the relationship, Coccio said, “and that came out of improv…which is great.” Another moment came near the close of “Zero Day,” when Andre and Cal end their killing spree. “I had written that scene several ways,” Coccio remembered. And at the point when the boys were about to shoot themselves, Andre came to him and said, “I’d like to try something, if you’d let me.” Coccio agreed, and Andre and Cal did a routine discussing the count on which they’d simultaneously fire–which Coccio decided to use. “There’s something about it that struck me as how it would be,” he said, “and if something felt right, I’d embrace it.” The morbidly humorous effect at so dramatic a moment is bracing, though. “I have very mixed feelings of pride and shock when the audience responds to that,” Coccio admitted.

In one of the final entries to their video diary, Andre and Cal emphasize that it will be fruitless for those who study their case to look for reasons behind their act, and that’s something that Coccio wanted his film to address. He recited the laundry list of causes proposed for the Columbine massacre and said, “These are pat answers. Even if they’re part of the equation, it’s ridiculous to grab onto something and determine that this one thing is the most important. And everybody kind of did that after Columbine, everybody who had an agenda. If you were for gun control, it was guns. If you were for more security in high schools, it was that the security was lax. If you were against violent movies, it was violent movies. Maybe you would say it was because they were picked on. Since there’s no good explanation, everybody’s going to come up with a personal one. So I wanted to accomplish that with the film–I wanted not to give any answer. I don’t think there is one answer. And that’s one of the most difficult things for the American psyche.” As far as Andre and Cal are concerned, their creator said, ultimately they remain an enigma. “As close as you’ve gotten to them over eleven months [of their video diary],” he observed, “there’s just a part of them that you couldn’t have known.”

“Zero Day” is an Avatar Films release.