He was consecrated as the Armenian Apostolic bishop of Caffa[a] by the Caucasian Albanian catholicos Stepanos IV in or before 1321.
The papal bull Doctor gentium egregius of Pope John XXII, dated 22 November 1321, refers to him as "the son of perdition ... who separated from unity with the church."
[1] The question of the chronology of the Catholic bishops of Caffa in this period is somewhat confused.
In a letter to King Leo II of Armenia dated 1323, Marino Sanudo Torsello writes that "Brother Thaddeus and his associates, your envoys, who are now at the Roman curia, will be able to report to you orally when they return to you" about how Sanudo was pleading for assistance to the Armenian kingdom.
[5] Paul Riant, in editing the Ystoria de desolatione et conculcatione civitatis Acconensis et tocius terre sancte, a Latin account of the fall of Acre in 1291, proposed that its author, Thaddeus of Naples, was identical to Thaddeus of Caffa.