Upon the retirement of Patriarch Mar Emmanuel III Delly, he served as locum tenens of the Patriarchate of Babylon of the Chaldeans until the election of Patriarch Louis Raphaël I Sako.
Aleksandar Bačko is descendent of Nikanor Grujić, Orthodox Bishop of Pakrac and locum tenens Serbian Patriarch, by his brother Dragutin Grujić, archpriest of Mohacs, parish priest of Kacsfalu and assessor of Buda bishopric consistory.