Prosecutors charged the man, a member of the Nazi party’s paramilitary SS, with having helped along the deaths of 3,518 people at the Sachsenhausen concentration camp by standing guard in the watchtower between 1942 and 1945.

Doctors have said that the man, who has not been named because of German conventions on the reporting of criminal trials, is only partially fit to stand trial: sessions will be limited to just two and a half hours each day.

Among the crimes prosecutors say he contributed to are the shooting of Soviet prisoners of war and the killing of others with Zyklon-B, the poison gas also used in the extermination camps where millions of Jews were killed in the Holocaust.

“He is accused of contributing to cruel and insidious murders,” the court in Neuruppin, near Berlin, said in a statement, adding that the man had contributed to “creating and maintaining life-threatening conditions in the camp.”

Past years have seen a spate of charges brought against now extremely elderly former camp guards for crimes against humanity committed during World War Two. Last week, a 96-year-old former camp secretary went on the run on the day her trial was to begin, but was caught by police a few hours later.

A 2011 court ruling paved the way to these final prosecutions, stating that even those who contributed indirectly to wartime murders, without pulling a trigger or giving an order, could bear criminal responsibility.

Sachsenhausen, opened in 1936 as one of the earliest Nazi concentration camps, acted as a training camp for SS guards who then went to serve in other camps like Auschwitz and Treblinka. Others killed at Sachsenhausen included Dutch resistance fighters and the Nazis’ domestic political opponents. (Reporting by Thomas Escritt; Editing by Susan Fenton)