Siri then studied at the Pontifical Gregorian University in Rome, and was ordained to the priesthood by Archbishop Carlo Minoretti on 22 September 1928.

Finishing his studies at the Gregorian, he earned his doctorate in theology summa cum laude and also did pastoral work in Rome until autumn 1929.

In addition to his academic duties, Siri was a preacher, public speaker, and professor of religion at the classical lyceums named to Andrea Doria and Giuseppe Mazzini from 1931 to 1936.

[1] Alongside Archbishop Marcel Lefebvre and Cardinals Alfredo Ottaviani and Thomas Cooray, he was part of the association of traditionalist Council fathers named Coetus Internationalis Patrum but Siri commented, "I would describe myself as an independent, a man who walks alone and is not a member of any group.

[4] Media reports suggested that Siri in fact topped the first count of votes in the August 1978 conclave before losing to Albino Luciani, who became Pope John Paul I.

Vaticanologists suggested that the eventual winner, Cardinal Wojtyła, who became Pope John Paul II, was chosen as a compromise candidate between the two.

"[7] Siri reached age 80 in 1986 and thus lost the right to participate in future conclaves; he was the last remaining cardinal elector who had been elevated by Pope Pius XII.

Siri was considered a strong candidate in the 1958 papal conclave held to elect a successor to replace Pius XII.

[8] On the evening of 26 October, the first day of the conclave, apparent white smoke was seen coming from the chimney of the Sistine Chapel, a traditional signal to the crowds in the square outside that a pope has been elected.

[8] Sometime in the late 1980s, an American traditionalist Catholic named Gary Giuffre began to expound the belief that Siri was the true pope and that he was held captive in a monastery in Rome.