German authorities have rejected a former Auschwitz death camp guard’s bid for clemency, removing the final barrier to him serving his sentence for accessory to murder.

Lueneburg prosecutors’ spokeswoman Wiebke Bethke said Wednesday her office had rejected former SS sergeant Oskar Groening’s clemency request filed earlier this week. She said regulations prevented her from releasing any further details.

The 96-year-old was convicted in Lueneburg in 2015 as an accessory to the murder of 300,000 Jews and sentenced to four years in prison. He hasn’t yet spent any time behind bars because of the appeals process.

Hannover prosecutors, who have been handling his case, are expected to soon summon him to begin serving his sentence.

A doctor had previously declared Groening fit to go to prison, as long as appropriate medical care is available.

Groening exhausted his last chance at legal appeals in December when the country’s highest court rejected his attorneys’ argument that imprisoning him would violate his constitutional right to life and physical safety.

The Federal Constitutional Court noted, however, that German law allows for prison sentences to be interrupted if a prisoner’s health deteriorates significantly.

Groening, who has been dubbed the “accountant of Auschwitz,” testified at his trial that he oversaw the collection of prisoners’ belongings and ensured that valuables and cash were separated to be sent to Berlin. He said he witnessed individual atrocities, but did not acknowledge participating in any crimes.

The court that convicted him ruled, however, that he was part of the “machinery of death,” helping the camp function, and collecting money stolen from the victims to help the Nazi cause, and thus could be convicted as an accessory to the murders committed there.

(AP)