The family of John Demjanjuk has appealed a prosecutor’s decision to shelve an investigation into his death while awaiting an appeal on a Nazi war crimes conviction.

Bavarian prosecutors last week closed the investigation into whether pain medication given to Demjanjuk exacerbated his kidney problems, saying no evidence was found of medical errors.

But in the appeal filed Tuesday, Demjanjuk’s attorney says the decision contradicts “all medical knowledge” about the drug Novalgin, which is commonly used in Germany but has been banned in the U.S. and elsewhere over safety concerns.

Demjanjuk’s family is asking that charges be brought against five doctors and a nurse.

Demjanjuk was convicted in 2011 of serving as a death camp guard, which he always denied. He died in March at 91 while awaiting an appeal.

(AP)