Oskar Groening’s job was simple: He counted stolen money and guarded the belongings of thousands of Jews who were brought to Auschwitz to be murdered.

To Groening, he was just a “cog in the machine.” After all, “just being a member of a large group of people who lived in a garrison where the destruction of the Jews took place” doesn’t make you a criminal, he has asserted.

So for years, Groening tried to draw as little attention as possible to the crimes he witnessed. He largely succeeded until later in his life, when he started to speak up.

“We obviously knew that the things that had happened there did not necessarily comply with human rights,” he told PBS for the documentary “Auschwitz: Inside the Nazi State.

Perhaps it was guilt, or a bid for exoneration, or a shrewd strategy to turn the horror of his past into currency that could redeem his future. But Groening was stoic and often brutally forthcoming about what he witnessed at that Nazi death camp, and he came to be known as one of the few living SS officers willing to speak up against Holocaust denial.

At the same time, the “Accountant of Auschwitz” has always rejected claims that his presence as a “loyal” SS officer amounted to a crime.

At the age of 93, now nearing the end of his life, he will finally find out whether the law is on his side.

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During the first day of court proceedings in Lueneburg, Germany, on Tuesday, sitting before an audience that included Holocaust survivors, Groening admitted a profoundly important truth.

“I share morally in the guilt,” he said at the outset of his testimony, according to the BBC. He asked “for forgiveness.”

“But whether I am guilty under criminal law, you will have to decide,” he said.

Auschwitz survivor Hedy Bohm, left, and her daughter, Vicky Bohm, leave the court during a break in the trial. (Markus Schreiber/AP)

Groening has evaded prosecution in the past. According to the BBC, charges were dropped against him in the 1980s because prosecutors determined that there wasn’t enough evidence of his personal involvement in the killings.

But in 2011, according to the BBC, a critical court ruling set a new precedent that paved the way for Groening and others to be charged as accomplices — even if they might not have actually carried out the murders themselves.

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“It is a black stain on Germany’s map,” Christoph Heubner, the executive vice president of the International Auschwitz Committee, told NBC News. “The culprits were welcomed in the midst of society, and the general public kept silent. Groening was a wheel in the murder machine of Auschwitz and therefore also had blood on his hands.”

Groening’s trial puts that idea to an important test: Does counting the stolen money of Jewish prisoners make someone complicit in their murders? By standing watch over their belongings, is he just as guilty as a guard who kept them locked in their quarters?

Those complex legal questions will be answered in the proceedings that are expected to go on until July.

“By sorting the bank notes, he helped the Nazi regime to benefit economically,” said Jens Lehmann, who is representing the plaintiffs who are Auschwitz survivors or relatives of victims, according to Reuters.

Groening is now a widowed father of two who moves around with the help of a walker and is hard of hearing. During the Holocaust, he was assigned to work at Auschwitz before he knew of the horrors that occurred there. But he wasn’t an unwitting participant: Eager to rise in the Nazi ranks, he threw himself into the “bookkeeping” job that he had been given, he told the court according to the BBC.

This undated photo made available by the Auschwitz-Birkenau Memorial and Museum in Poland shows Oskar Groening as a young man. (Museum Auschwitz-Birkenau/AP)

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Between May and June 1944 more than 300,000 Jews were gassed to death, according to the Telegraph. In that time, Groening constructed in his own mind ways of rationalizing the atrocities going on all around him.

The money and bank notes he handled didn’t belong to the Jewish prisoners; it was “money without owners,” he told Der Spiegel in 2005.

Groening believed in Adolf Hitler and agreed with him that winning the war required the extermination of Jews.

“That it was a tool of waging war. A war with advanced methods,” he told Der Spiegel. “Unfortunately, it just happens to be the case that they took me, Oskar Gröning, to this camp where the things that everyone was cheering about were actually happening.

“And then, at some point you are there and the only thing left is the feeling: I am part of this necessary thing. A horrible thing — but necessary.”

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On Tuesday, Groening repeated the appalling stories he has told matter-of-factly in the past.

He spoke of witnessing an SS officer murder a small Jewish baby whose cries annoyed him.

He talked about participating in — no, witnessing, he said, correcting himself — the gassing of Jewish prisoners, according to Reuters:

He also told of an incident in late 1942 when he witnessed naked Jews being herded into a converted farm house near the camp. A fellow officer shut the door, put on a gas mask, opened a can and poured its contents down a hatch.

“The screams became louder and more desperate but after a short time they became quieter again,” Groening said.

“This is the only time I participated in a gassing,” he added, before correcting himself: “I don’t mean participated, I mean observed.”

Groening may be one of the last Nazis to stand trial for Holocaust crimes. If convicted, he faces up to 15 years in prison.

That sentence could be longer than Groening will ever live. But for survivors of Auschwitz, justice — no matter how late — matters.

“No survivor, and for that matter no one, should conclude that at least the ones who took part in inflicting such unspeakable suffering should be allowed to evade justice merely because of their prolonged success in eluding detection,” Roman Kent, Auschwitz survivor and former president of the International Auschwitz Committee, said in a statement in 2013. “In addition, there is also an important reason to pursue the Nazi criminals, namely to help prevent the repetition of such ghastly crimes.

“The Nazi prosecutions send an unmistakable warning to would-be perpetrators that if they dare to act and commit mass murder there is no real chance for them to get away scot-free.”