Forget about "The Conjuring": no movie has brought more true horror to the screen this year than the documentary "The Act of Killing," which opens in Los Angeles on Friday after bowing in New York last week.

In director Joshua Oppenheimer's film, Indonesian gangsters recreate government sanctioned killings of as many as 1 million communists, left-wingers, union workers and others nearly 50 years ago. And they do it in the style of their favorite films.

Surreal, horrifying and utterly unlike any other film on this kind of subject, the Drafthouse Films release features harrowing film-noir sequences in which the gangsters portray their own victims as they reenact the killings, as well as bizarrely lavish musical numbers in which the dead thank their killers. The killers have openly bragged about their deeds for decades, but the film shows a few of them grappling with the memory – notably Anwar Congo, head of a group of Northern Sumatra gangsters obsessed with the movies, who suddenly begins retching, gagging and shaking with the dry heaves when he returns to the rooftop where he'd strangled hundreds.

TheWrap wrote about the film after it premiered at Toronto last September, when Oppenheimer (above) said he'd been approached before a screening by two men from the Indonesian embassy who'd warned him, "We're following this film very closely."

Also read: Horrifying Toronto Doc 'Act of Killing' Restages Mass Killing as Twisted Entertainment

Since then, "The Act of Killing," executive produced by iconic documentarians Werner Herzog and Errol Morris, has been shown in private screenings there. Oppenheimer talked with TheWrap about the death threats he has received and the ongoing need to protect the identify of people in the film, lest they face reprisals in a country where for 47 years the government has either officially denied that the massacre took place, or claimed it was justified.

When we spoke in Toronto last September, you didn't know how you were going to release the film in Indonesia.

We knew that if we just submitted it to the censors and it was banned, then it would become a crime to screen it. And that would become an excuse for the [government-sanctioned] paramilitary group or the army to attack screenings with impunity. But once it became a big news story during Toronto, we realized that we needed to get the media to see the film. So we started screening right after Toronto. We told everybody, "Why don't you hold screenings, but do it by invitation?" On the 10th of December last year, which was International Human Rights Day, there were 50 screenings in 30 cities, ranging in size from 30 people to 600 people. By the first of April, there had been more than 500 screenings in 95 cities.

What has the reaction been?

We held screenings for Indonesia's leading news publishers, producers, editors, filmmakers, historians, educators, human rights advocates, artists, writers, survivors' groups all through the autumn, and everybody really loved the film. But the most powerful reaction was from the editors of Indonesia's leading news magazine, Tempo. They decided that the film was so important for them that they had to break what had been a decades-long silence about the killings.

They sent dozens of journalists around the country to show that "The Act of Killing" was a repeatable experience, that they could find men who would boast about what they had done. They gathered something like 500 or 600 pages of boastful testimony from perpetrators, edited it down to 75 pages and gathered another 25 pages of material about the film. And that really set the tone for the mainstream Indonesian media to say, "We need to talk about this."

The film has really come to Indonesia like the child in the Emperor's New Clothes, which is how I intended it. That's been the most wonderful thing – pointing at the king and saying, "Look, the king is naked." Everybody knew it and had been too afraid to say it, but now that it's been said so undeniably, there's no going back. The moral consensus around these events has really shifted.

I don't think the killings are particularly well-known in the United States, but the film suggests that the U.S., which was desperate to halt the spread of communism in Asia at the time, was complicit in what happened.

The U.S. was absolutely complicit. The U.S. provided money, provided weapons, provided lists of people they wanted dead. They encouraged the army to kill everybody on the left, or put everybody on the left in political prisons as a way of making sure that the whole left was annihilated.