Reinhold Hanning, 93, is alleged to have joined Adolf Hitler's Schutzstaffel (SS) paramilitary organisation at the age of 18, taking part in battles in eastern Europe before becoming a guard at the camp in 1942.

Around 1.5 million people, mainly European Jews, were gassed, shot, hanged and burned at the camp in what was then Nazi-occupied Poland during the Second World War.

Accused by prosecutors in Dortmund and 38 complainants from Hungary, Israel, Canada, Great Britain, the United States and Germany, Hanning will face accounts of camp survivors who witnessed the killings.

Erna de Vries, who in 1943 at the age of 23 was deported to Auschwitz along with her Jewish mother, was saved from the gas chamber as her father was Protestant.

"I survived, but up until today I don't know how exactly my mother was killed," she said ahead of Hanning's trial.

"The last thing she said to me was: 'You will survive and tell what happened to us.'

"I am not hateful but it somehow feels like justice to see this man, who was working there when my mother died, on trial."

Hanning has denied involvement in the killings, but prosecutors allege he also served at Auschwitz's Birkenau sub-division where nearly all of 1.2 million killings in the camp were carried out in four gas chambers.

His trial will be the first of four such court cases that could be the last due to the age of the defendants.

The three men and one woman accused are all in their nineties and will be tried over the next few months, starting with Hanning's appearance before a court in the German city of Detmold.

War crime investigator Efraim Zuroff from the Simon Wiesenthal Centre in Los Angeles said age should not preclude prosecution of people implicated in the deaths of Auschwitz's prisoners.

"When you think of these cases, don't think of frail, old, sick men and women, but of young people who devoted their energies to a system that implemented the (Nazis' so-called) Final Solution and aimed to obliterate the Jewish people."

newstalk.com