A 93 year-old man who served as a guard at Auschwitz concentration camp was charged with 300,000 counts of accessory to murder on Monday.

Oskar Groening was an S.S soldier working at the Nazi death camp for two and a half years, during that time it is believed that 425,000 Hungarian Jews were held, 300,000 of those were gassed to death.

Goening’s job at the camp was to deal with the belongings stolen from camp victims, including helping to collect and record stolen money. State prosecutors said in a statement, “He helped the Nazi regime benefit economically, and supported the systematic killings.” Groening has said he witnessed killings but did not commit any crimes.

Regardless of his actual participation in the killings, prosecutors said he was a willing cog in a machine of mass murder.

After learning of holocaust denials, Groening made his association with Auschwitz public and has openly criticised those who deny the events. In an interview with the German news magazine Der Spiegel in 2005, he described seeing an SS soldier pick up a baby by the legs “He smashed the baby’s head against the iron side of a truck until it was silent,” Groening said, “I went to my superior officers and made an application for a transfer to the front, to anywhere. But he refused. Down the years I have heard the cries of the dead in my dreams and in every waking moment. I will never be free of them.”

Last year federal investigators recommended that prosecutors pursue charges against 30 former Auschwitz guards in a last push to bring Nazi war criminals to justice. Goening is the fourth case to be investigated, two have been halted after the suspects were said to be unfit for trial.

The Auschwitz concentration camp was first built to hold Polish political prisoners, who began to arrive in May 1940. The first exterminations took place in September 1941. From 1942 until the end of 1944, trains delivered Jews to the site from all over Nazi-occupied Europe. It is believe that at least 1.1 million prisoners died at Auschwitz, many gassed with the pesticide Zyklon B.