You know the subject matter for your documentary is exceptional when you have both Werner Herzog and Error Morris listed as executive producers. This is the case with Joshua Oppenheimer’s The Act of Killing—a powerful documentary about Indonesia’s violent history from roughly fifty years back when more than a million of alleged hostile Communists were wrongly murdered. What helped the documentary earn such strong critical support is that it reenacts the horrific mass murders that took place from the most creditable source; the murderers themselves. The Act of Killing feels like a completely fresh take on the documentary genre by letting the subjects have full control, making the film-within-a-film not feel gimmicky, and rids itself of preachy narration to exemplify the message.

The Act of Killing begins by providing historic details behind the mass murders in Indonesia by a military coup in 1965. Back then the Indonesian government was overthrown a military group who accused anyone who opposed the dictatorship of being a communist. This army used paramilitaries and local gangsters to carry out the killing of over one million accused “communists”. The documentary follows several individuals who were responsible for these murders and offers them to a chance to recreate scenes about the killings in whatever way they wish; that is when The Act of Killing becomes horrifically fascinating.

The main focus of the documentary is a man named Anwar Congo—one of the most feared gangsters of that time period. Congo proudly recalls the mass murders he was responsible for back when he as a ruthless member of the paramilitary group called Pancasila Youth. Eventually he admits that his sleep is affected by the killings and that is where the documentary beings to reveal its agenda. At first he justifies what he did by looking at it from the perspective of freeing the individuals by sending them to heaven. But the reenactments end up hitting a note a little too close to home, even for the murderers.

What really makes the documentary work is how hands-off Oppenheimer is with his subjects. Instead of steering them into any set direction, he simply allows them to decide how they want to present the “truths”. In doing so, he was able to capture the conflicts they had with each other about what to show. At one point a debate breaks out on whether or not they should reveal the real motive behind a certain scene and someone declares, “Not everything true should be made public.” By keeping an arm’s-length away it allowed the gangsters to come to their own realizations without the aid of Oppenheimer to force it upon them.

The Act of Killing serves up a bone-chilling look at how comfortable a group of mass murderers are with justifying their shockingly violent past. They were never punished for murdering thousands of people because of the consequences someone would face if they did, even today. By allowing these men to recreate their murders, Oppenheimer is able to capture an unsettling point of view. At the same time, he briefly exposes the corruption in their current political system as citizens are still being paid for their vote. The length of the documentary is felt just before the final conclusion, but it is such a triumph that it makes it well worth the wait.