Updated

Oskar Groening, the death camp guard known as the “bookkeeper of Auschwitz,” died on Friday — before he was able to start his four-year prison sentence, according to multiple reports Monday. He was 96.

Groening, a former SS sergeant, was convicted in July 2015 of being an accessory to the murder of 300,000 Jews. He was expected to start his four-year prison sentence, but died at a hospital on Friday, the Jerusalem Post reported, citing Germany's Der Spiegel.

German prosecutors deemed Groening to be fit enough to go to prison as long as there was appropriate medical care. A federal court rejected Groening’s appeal in November.

The 96-year-old's lawyer had argued Groening was too frail to go to prison. He submitted a request for clemency in early March.

It was unclear when Groening would have begun his prison sentence.

The Associated Press contributed to this report.