John Gonzales de Castrillo was born at Sahagun, Leon Spain. He was educated by the Benedictine monks of Fagondez monastery there and when twenty, received a canonry from the bishop of Burgos, though he already had several benefices. He was ordained in 1445; concerned about the evil of pluralism, he resigned all his benefices except that of St. Agatha in Burgos. He spent the next four years studying at the University of Salamanca and then began to preach. In the next decade he achieved a great reputation as a preacher and spiritual director, but after recovering after a serious operation, became an Augustinian friar in 1463 and was professed the following year. He served as master of novices, definitor, prior at Salamanca, experienced visions, was famous for his miracles, and had the gift of reading men’s souls. He denounced evil in high places and several attempts were made on his life. He died at Sahagun on June 11, reportedly poisoned by the mistress of a man he had convinced to leave her. He was canonized in 1690 as St. John of Sahagun. His feast day is June 12th.