John was born in Tuscany. He was an elderly archdeacon at the time of his election as bishop of Rome in 523. His brief pontificate was caught up in the violent politics of the age. He was sent by the Gothic King of Italy, Theodoric, who was an Arian heretic, on a mission to Byzantium to secure mutual toleration between Catholics and Arians, and to try to bring the Eastern and Western Churches closer together. Theodoric suspected him of conspiring with Emperor Justin in Constantinople and imprisoned him at Ravenna on his return. He died shortly afterwards in 526 and is venerated as a martyr. – CTS New Daily Roman Missal 2012, p 2691; Christian Prayer 1990, p 1132.
