A verdict is due on Tuesday in the case of Josef S who is the oldest person to be tried for Nazi-era crimes.
The 101-year-old is accused of complicity in the murder of 3,518 prisoners at the Sachsenhausen camp, north of Berlin, between 1942 and 1945.
He faces up to five years in prison, a symbolic sentence that he will probably not serve because of his advanced age.
"I don't know why I'm here," the defendant said on Monday. "I'm telling the truth. I have nothing to do with the police or the army, everything that was said is false."
Dressed in a grey shirt and pyjama bottoms, he entered the courtroom in Brandenburg-sur-la-Havel, 70 kilometres west of Berlin, in a wheelchair.
"At 101, he is the oldest defendant in German history, so I ask for his acquittal," said his lawyer Stefan Waterkamp.
"We don't have a photo of him in an SS uniform" but only have "hints" of his possible activity in Sachsenhausen, he said.
"As early as 1973, investigators had information about him but they did not prosecute him. At the time, witnesses could have been heard, but now they are all dead or no longer able to speak.
"The danger of this court would be to try to make up for the mistakes of the previous generation of judges."
"This person is very old, he does not want to remember," said Antoine Grumbach, 80, whose father, involved in the resistance in France, died at Sachsenhausen.
"It is a form of defence. But it is not very serious because for me there is no question of putting a centenarian in prison.
"The most important thing is the fact that we were able to collect and show to the general public all the documents which prove that Sachsenhausen was an experimental extermination camp: all the cruellest methods were invented there and then
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