Anwar Congo is an unlikely international celebrity. A former gangster who dropped out of school in the fourth grade, the septuagenerian Indonesian is the star of The Act of Killing, a spectacular new documentary that just opened in the U.S. In the film, Congo admits to killing hundreds of people in cold blood, with a smile on his face. It's perhaps not a surprise that he's expressed some displeasure with the film, but his reasons aren't what you might expect.

The Act of Killing is going to be one of those few documentaries that break into Herzogian levels of public awareness. This is not only because it has the blessing of both Werner Herzog and Errol Morris. The Act of Killing is the most gripping documentary I've ever seen, and judging from its current 100% rating on Rotten Tomatoes critics agree. (You can watch a clip here.)

The film's brilliance starts with its premise: Director Joshua Oppenheimer had Indonesian gangsters stage reenactments of the mass killings they took part in during the 1965-1966 anti-communist purge, which left an estimated half million people dead, complete with their own scripts, elaborate costumes and special effects. The glee with which the aging killers re-live the days they strangled victims, coldly shot them as they begged for their lives, raped their daughters before burning down their homes, etc., conveys the horror of the real events more engagingly than any eyewitness testimony, without exploiting the victims' suffering. The premise also dramatizes Indonesia's inability to come to terms with the massacres, which were at least tacitly endorsed by the U.S. government, happy to get rid of communists by any means necessary at the height of the Cold War. The perpetrators of the massacres are not only free to boast about their deeds on camera, many of them hold influential positions in Indonesian society. (Read Errol Morris' fascinating essay in Slate about the killings for more background.)

"It's about how a traumatic past remains alive in the present and continues to traumatize society and therefore enable corruption and a regime of fear," Oppenheimer told the Wall Street Journal of his film.

Anwar Congo is the film's human symbol of Indonesia's traumatic past. It's easy to see why Oppenheimer chose to make a star of Anwar Congo, now 72. On camera Anwar is charming, almost goofy, with a big smile and a naiveté that seems to mask a secret cunning. Contrast his gentle character with the terrible deeds he describes—he proudly claims to have personally killed a thousand people—and you've got cinematic gold. During the purge of 1965-1966, Anwar worked at a movie theater and was a member of the Pancasila Youth, one of the paramilitary groups that helped carry out the killings. The movie begins with Anwar rounding up his old Pancasila buddies to participate in the reenactments, as if he's getting the old college softball team back together. In one of the most disturbing scenes, Anwar giggles while demonstrating how he strangled to death countless communists with a wire on a quiet concrete rooftop, a technique he learned from the American gangster movies he loves. But by the end of the movie, which spans five years, this portrait is complicated when Anwar is overcome by the violence he committed to the point of physical sickness.

After I watched the The Act of Killing I wanted to know more. Not about the history of the killings, but about the making of the film itself. It's such a complex document, so multilayered and self-reflexive, that the story behind the movie is even more compelling to me than the story it tells. Mainly, I wanted to know what Anwar Congo thought of a movie that baldly portrayed him as a villain. The utter self-consciousness with which he speaks of what he did makes it hard to believe he could object to anything in the movie. But I know from experience that people can begin to see even their own words as devious traps once they've been documented.

The Act of Killing actually attempts to address the question of what Anwar thinks of the film. In one scene towards the end of the movie, Congo watches some of the reenactments he's participated in. He beams with pride and even calls his young grandsons in to watch as his onscreen "character" strangles a communist. His main complaint seems to be with the wardrobe choices. The message is clear: Anwar is happy. His image of himself aligns with Oppenheimer's.

But the story since The Act of Killing's release has beeen more complicated. In Indonesia, Anwar briefly waged a sort of PR campaign to denounce it. Soon after the film premiered at the Toronto International Film Festival in September, the Jakarta Post reported that Anwar and another subject of the film, Sakhyan Smara, were considering suing Oppenheimer. They said they were misled. The movie, they claimed, was "fictional and not intended for public viewing."

Anwar told the Post that throughout the filming he believed he was playing the male lead in a fictional film called Arsan and Aminah, about a couple who falls in love during the anti-communist purges. Only later was the name changed to The Act of Killing and transformed into a documentary, he said. Sakhyan said Oppenheimer told him that he wanted to examine the purges as part of his doctoral degree studies, so he believed it wasn't for public consumption. None of these preliminary discussions are shown in The Act of Killing, which starts with Anwar recruiting people for the film.

A few days later, Anwar Congo appeared at a press conference held by the Pancasila Youth in which he again claimed he'd been duped by Oppenheimer. "I feel cheated," he told the assembled media, posing in front of a slick Hollywood-style poster for Arsan and Aminah.

Notably, Congo and his fellow subjects do not deny that they took part in the killings, or attempt to backtrack on what they said in the film. "I joined the anti-PKI drive because PKI was our common enemy," Anwar told the Jakarta Post, refferring to the initials of Indonesia's communist party. Another main subject, Adi Zulkadry, said he had no regrets about his real-life massacres, either: "This is the will of history," he said at the press conference. So why did Adi not like the movie? "The movie was commercialized," he said. "[Oppenheimer] made money, I will not get anything."

Basically they're arguing over artistic control of The Act of Killing: Where the movie purports to show its subjects creating reenactments for the sole purpose of the documentary, Anwar and his buddies say they were making their own movie with the Oppenheimer's help, which then got co-opted by Oppenheimer for his project. It's a strangely old-fashioned showbiz squabble.

Oppenheimer has strongly denied his subjects' claim in a lengthy rebuttal, which he emailed to Caroline Cooper, who wrote about the film for Guernica.

"As it says at the beginning of the film, Anwar… and the others always knew they were only making scenes for my film, and were never making a film of their own," Oppenheimer wrote. Oppenheimer said the movie was never called Arsan and Aminah, and the name was the title of one of the reenactment scripts that a subject of The Act of Killing had written for the movie. The subjects all signed agreements explicitly saying that they were not making their own films.

As for Anwar's displeasure at the film in which he appears so comfortably, Oppenheimer writes he believes Anwar's displeasure is an act put on for the Pancasila Youth. The group, which is still powerful in Indonesia, comes off poorly in the movie and may be pressuring Anwar to distance himself from it.

What's more, all of Anwar's criticisms, he said, were made before actually viewing the film. Oppenheimer offered a detailed description of Anwar's first viewing of the movie, after which he seemed to change his mind considerably. On November 2012, an Al Jazeera journalist showed Anwar the film in a hotel room in Jakarta, as part of a report on the film. Afterward, Anwar spoke to Oppenheimer over Skype. He wrote:

"We were both, I think, very nervous... He was wearing sunglasses, even though he was indoors, in the hotel room. I must have looked serious, and worried, because I was, and Anwar said, “Come on Josh, smile.” I asked, “You want me to smile?” “Yes please,” he said. I smiled for him. I really wanted to know what he thought of the film, how he was feeling, so I asked, “Anwar, please take off your sunglasses.”

He took off his sunglasses, and it was like losing his armour, like when the children leave him as he is watching himself play the victim near the end of the film. He started to cry. Tearfully, he told me that the film showed honestly what he knew the film would show, what he had tried to show in the film. “This is the film I expected,” he told me. “It’s an honest film, a true film”, he said. He continued, saying that he was profoundly moved by the film, and will always remain loyal to it.

I asked him how he felt during the screening, and he said, “There is nothing left for me to do in life but die.” What could I say? I tried to comfort him as best I could. “You’re only 70 years old, Anwar. You might live another 25 years. Whatever good you do in those years is not undermined by the awful things in your past.” It’s a cliché, but it felt honest and it was all I could manage.

In the Al Jazeera interview conducted after he saw the film, Anwar doesn't seem upset at Oppenheimer, or his past actions. When the interviewer asks if he's worried viewers might seem him as a bad guy he responded: "That's up to the viewers to decide…. I don't feel guilty."

The Act of Killing is an amazing movie and worth seeing regardless of whether Anwar likes it. But it's not a trivial question: If Anwar really does like the film, the fact that he would so readily change his story in response to outside pressure raises the question of why we should believe the spectacular claims he makes in The Act of Killing in the first place. And is it actually a good thing that someone who approves of massacring people approves of your portrayal of his massacring people? It's hard to say what he really thinks. Anwar alternates between extreme regret and extreme callousness, breaking down on mournfully camera during The Act of Killing, but telling journalists he doesn't regret a thing. Maybe this bipolarity is old trauma crossing the wires, or maybe Anwar's acting doesn't end with the campy reenactments.

Oppenheimer may have the last word for now. I wanted to get in touch with Congo for this post, so I emailed Khairul Ikhwan Damanik, an Indonesian journalist who interviewed Congo for an October cover story for the news magazine Majalah Detki. Khairul told me that Anwar had also told him he felt cheated by Oppenheimer. But that was before he'd seen The Act of Killing, and Khairul said he stopped doing interviews after Al Jazeera showed it to him. A Danish and Austalian journalists have recently approached him and were rebuffed, according to Khairul.

"The problem is, Anwar Congo doesn't want to interview with journalist, no more," Khairul wrote in the email. "He said enough."