According to Eusebius HE 5, 22, Demetrius was made bishop in the tenth year of Commodus 189 and governed for 43 years HE 6, 26, until 232. After Septimius Severus’s persecution, he entrusted the teaching of catechesis to the young Origen HE 6, 3, whose self-mutilation he initially approved but later condemned HE 6, 8. He encouraged Origen’s apostolic work HE 6, 14, but protested when Alexander of Jerusalem and Theoctistus of Caesarea allowed him to preach while still a layman, obliging him to return to Alexandria HE 6, 19.
When Origen, ordained priest during a second journey to Palestine, returned to Alexandria after disputing with certain heretics in Greece 230 231, Demetrius, offended by this ordination carried out by extraneous bishops, made Origen’s mutilation public and held a synod of bishops and priests which obliged the theologian to leave Egypt; with some other bishops, he declared Origen deposed from the priesthood Pamphilus according to Photius, Bibl. 118. Jerome, at that time still an Origenist Ep. 33, and Eusebius attribute Demetrius’s hostility to jealousy: evidence e.g., Origen’s letter To the friends of Alexandria seems to indicate that there may have been doctrinal concerns, as well.
Approved by Rome, Demetrius’s sentence was ignored by the bishops of Palestine, Syria, Arabia and Achaia Greece, who received Origen, recognizing his priesthood. Demetrius died shortly thereafter. Coptic sources give him a peasant origin and attribute to him some letters to Pope Victor and to the bishops of Antioch and Jerusalem on the date of Easter. The events of Demetrius’s relationship with Origen find an adequate explanation in the historical context of the passage precisely the work of the strong-willed Demetrius from a presbyteral to an episcopal hierarchical structure in the church of Alexandria. A. Harnack, Die berlieferung 1893, 330-332.