JACOBUS APELLA VICEDOMINUS (late 11th–mid-12th century), a baptized Jew of Prague who was chief administrator of Duke Vratislav of Bohemia (1110–40). His story was first told by the Bohemian chronicler Cosmas of Prague, but the historical basis of it is hard to determine. Apparently baptized in 1096, he made a dramatic return to Judaism in 1124, defiling an altar which had been erected in a synagogue and throwing Christian relics into a sink. Prague Jewry saved him from the death penalty by paying a high ransom.
Steinherz, in: JGGJČ, 2 (1930), 17–47.