Forty years after its release, Claude Lanzmann’s Shoah (1985) is regarded not just as one of the greatest documentaries ever made, but a film that had to be made in order to shake the world into engaging with its still recent trauma. A new documentary, however, shows how the French director’s seminal “fiction of the real” was almost never completed.

In preparation for All I Had Was Nothingness, which premiered this week at the Berlin film festival, French director Guillaume Ribot revisited the entire 220 hours of raw footage that Lanzmann filmed between 1976-81, before he then edited it down into the nine-and-a-half hour film released in cinemas. The outtakes reveal unseen insecurities and self-doubt on behalf of an auteur famed for his subsequent grandeur, all while coupled with an earth-shattering persistence and determination. It also frames Shoah as a classic case study of how the rules of journalistic ethics must sometimes be bent to expose the truth.

During the filming, Lanzmann, who died in 2018, was frustrated in several attempts to doorstep Nazi criminals such as Gustav Laabs, a driver of “gas vans” at the Chelmno concentration camp, north of the Polish city of Łódź. Prisoners at the camp were ushered into and then locked inside these mobile gas chambers before the vehicle’s exhaust pipe was connected to the interior of the van via a flexible hose. Drivers like Laabs then pressed the accelerator and let the engine run “for 10 to 15 minutes”.

Footage discarded by Lanzmann during Shoah’s four-year editing process show Laabs refusing to open his door to the film-maker and his crew, most likely because his neighbours had tipped him off about their arrival. “We are not at all interested,” one German man living in the same apartment building tells the director when informed that Laabs killed 200,000 Jews, adding: “What we don’t know doesn’t interest me at all.” Lanzmann mutters to himself in disgust as he walks away: “Mass complicity, truly.”

It was at this point Lanzmann decided he had to use subterfuge to get the Nazi criminals to open their doors. “He had to find a way to trick the tricksters, so to speak,” says Ribot. Realising his surname would immediately give away his Jewish heritage, Lanzmann used a fake passport with the name Claude-Marie Sorel. For his cover story, he gave himself a made-up PhD and set up the fictional Centre for the Story of Contemporary History, telling Nazi criminals he wanted to speak to them for a research project.

He loosened up his interviewees with lavish meals, paid them a fee (schmerzensgeld, or “damages”, as one war criminal calls it with unknowing irony), and repeatedly promised that he would not divulge their identities in his film. Unbeknown to the former German officers, he filmed their conversations via a small cylindrical camera hidden in the handbag of his translator, transmitting the footage to a van with recording equipment parked outside.

On one occasion, his cover was blown. During an interview with Heinz Schubert, an SS officer who oversaw a massacre of Jewish prisoners in the Crimean town of Simferopol, the war criminal’s wife checks on the van outside and notices the moving antenna. The camera cuts out, but a ghostly audio track documents the subsequent confrontation. “You’ve played a dirty trick on us,” Schubert’s relatives accuse Lanzmann, before bundling him out of their apartment.

Shoah’s use of subterfuge was debated after the film’s release in 1985, and again upon the publication of Lanzmann’s memoir The Patagonian Hare in 2009 (passages from which Ribot reads out to provide his film’s sole voiceover). The consensus at the time was that bending the rules of journalistic ethics was justified given the enormity of the crimes carried out by these men, and because the evidence against was not merely prima facie but had been accepted at the Nuremberg trials.

Forty years after Shoah’s release, Ribot says that consensus still holds. “I do agree with these methods, because the most important thing for Lanzmann, for me, is the possibility of getting to the truth, no matter what the methods that you need to use in order to do so,” he says.

“Nowadays, in the era of the smartphone, not only whistleblowers but all of us would use such a recording to denounce or to expose the situation, and nobody would criticise us for doing so,” he adds.

What had surprised him over the three months he spent watching Lanzmann’s original footage, Ribot says, was how much doubt the director had about the shape and purpose of his career-defining work. Fellow director and former friend Max Ophüls famously called him a “megalomaniac”, but in the first years of filming Lanzmann often seemed uncertain of what he wanted to do.

Originally commissioned by Israel’s foreign ministry as a two-hour film, officials withdrew funding after a few years out of frustration with Lanzmann’s slowness. A pitch for financial support in front of the American Jewish Committee, the director admits in his memoirs, were a “total failure” because he couldn’t sum up what the message of his film would be. “If I’d said, ‘never again’, or ‘love one another’, wallets would have sprung open. But I was a lousy fundraiser.” Not a single US dollar financed the making of Shoah.

In the end, All I Had Was Nothingness at least hints that it was the continued rejections and the undiluted antisemitism Lanzmann experienced at the hands of his interviewees that spurred on and shaped his masterpiece. In one scene that ended up on the cutting-room floor, a Polish peasant casually explains the local populace’s attitude to the atrocities that happened around them: that the mass-killing of Jews was an expiation for the crucifixion of Jesus.

“It’s an element that is deeply rooted in the popular culture, adding to a feeling of relativity about what has happened,” says Ribot. “It implies a religious justification, that the Jews somehow deserved what they got.”