A 93-year-old former Nazi SS guard, known as the "Bookkeeper of Auschwitz", has admitted he is "morally" guilty.
Oskar Groening spoke at the beginning of his trial for being an accessory to the murder of at least 300,000 Jews at the concentration camp.
He described his role of counting money confiscated from new arrivals and said he witnessed mass killings, but denied any direct role in the genocide.
If found guilty he could face three to 15 years in prison.
Addressing the judges, Mr Groening also said: "I ask for forgiveness. I share morally in the guilt but whether I am guilty under criminal law, you will have to decide.''
Oskar Groening looked frail as he entered the courtroom leaning on a walking frame. But his voice was strong and steady as he spoke for nearly an hour.
Four survivors from the notorious death camp faced him across the room. Much of his testimony described his attempts to achieve his ambition of being an SS "executive", to work as a bookkeeper for the Nazis.
But there were haunting moments too; for a little while we saw the horrors of Auschwitz through his eyes.
The survivors watched him impassively but their younger relatives shook their heads in disbelief as he recounted his arrival at the camp as a young SS guard. He'd been plied with vodka by officers there, he said.
He even described the vodka bottles. As they drank the officers told him that the camp was for deported Jews. That those Jewish prisoners would be killed and disposed of.
Later, he pulled out a water bottle: "I'll drink from it like I drank from those vodka bottles in Auschwitz."
The nonagenarian only came to the attention of prosecutors following a decision to speak out against Holocaust deniers.
"I saw the gas chambers. I saw the crematoria," he told the BBC in the 2005 documentary Auschwitz: the Nazis and the "Final Solution".
"I was on the ramp when the selections [for the gas chambers] took place."
He spoke of witnessing an SS soldier murdering a baby, and how the treatment of the prisoners had "horrified" him.
But he said that at the time he believed that killing Jews - including children - was the "right" thing to do.
"We were convinced by our world view that we had been betrayed... and that there was a great conspiracy of the Jews against us."
http://www.bbc.co.uk/news/world-europe-32392594 http://www.bbc.co.uk/news/world-europe-32336353