It is the 70-year-old bishop's first appointment as a member of a Vatican dicastery. He served as the bishop of Augsburg and the German Military Ordinariate until he resigned in 2010.

Bishop Mixa's resignation was accepted a few weeks after he offered it, after accusations surfaced that he had hit children during his time as a priest in charge of a children's home near Augsburg. He originally denied the claims, then admitted that he had perhaps "boxed the ears" of some of his wards.

Bishop Mixa also faced accusations of misappropriation of funds from the children's home.

German prosecutors also investigated Bishop Mixa for alleged sexual abuse of a minor when he was bishop of Eichstatt from 1996 to 2005, but dropped the investigation for lack of evidence.

Pope Benedict met with Bishop Mixa after his resignation, in a private audience at the Vatican in 2010. After the closed-door meeting, the Vatican said the bishop would "retreat for a period of silence, contemplation and prayer."

After a period of "treatment and reconciliation," the Vatican had said the bishop would be available for pastoral work authorized by his successor, Bishop Konrad Zdarsa.