A verdict is due in the case of a former SS officer known as the Bookkeeper of Auschwitz, expected to be one of the last German trials of its kind.
A court in the northern city of Lueneburg, which has been hearing the case since April, is to read out its judgment on 94-year-old Oskar Groening from 7:30am on Wednesday (local time).
As the proceedings wrapped up on Tuesday with the defence calling for an acquittal, Groening seized a last opportunity to address the judges and said he was "very sorry" for his time stationed at the Nazi death camp.
"No one should have taken part in Auschwitz," he said.
"I know that. I sincerely regret not having lived up to this realisation earlier and more consistently. I am very sorry," he said, his voice wavering.
Groening stands accused of 300,000 counts of accessory to murder in the cases of deported Hungarian Jews sent to the gas chambers between May and July 1944.
If convicted, he could be sentenced to between three and 15 years.
However, few observers expect he would serve jail time given his advanced age and failing health, which led to several delays in the proceedings.
Groening served as a bookkeeper at Auschwitz, sorting and counting the money taken from those killed or used as slave labour, collecting cash in different European currencies, and shipping it back to his Nazi bosses in Berlin.
Groening has acknowledged "moral guilt" but said it is up to the court to rule on his legal culpability seven decades after the Holocaust.
Last week public prosecutors said they were seeking three and a half years' jail for Groening based on the "nearly incomprehensible number of victims", but mitigated by "the limited contribution of the accused" to their deaths.
They charge that on at least three occasions, Groening performed "ramp duty", processing deportees as they arrived in cattle cars at the extermination and forced labour camp in Nazi-occupied Poland.