A fanatical female guard at the Auschwitz-Birkenau extermination camp, now 90 years old, will stand trial for her role in assisting mass murder.

Prosecutors claim that the woman, only identified as Gisela S., was a harsh disciplinarian who often beat prisoners, and that she was frequently in charge of the standing cells, which were small, dark rooms in which numerous prisoners would be crammed — often for days or until death — after minor infractions.

Gisela S. is the latest in a new wave of prosecutions in Germany of Nazi guards, most in their 90s.

If convicted, she will be one of only a handful of the estimated 3,700 female guards employed by the Nazis to face justice. Gisela S. appeared at the 1960s trial of Auschwitz guards in Frankfurt but escaped jail time, reported The Daily Mirror.

She worked at the camp under her maiden name of Demming.

Gisela S. has been described as a die-hard supporter of the Nazi party, who joined the League of German Maidens before entering the SS in 1940.

A 93-year-old former medic at Auschwitz was also recently arrested and will stand trial according to reports on Tuesday. And a third former Nazi, Oskar Groening, last week was deemed fit to stand trial for his role at the camp. Groening, 92, was in charge of sending back to Berlin valuables and money stripped from arriving prisoners.