By 1940, he was listed in the city directory as Rev. Nikolaj Petkovich, pastor of St. Sava's Serbian Orthodox Church and resided 2107 Sidney Street, on Pittsburgh's South Side. In 1944, he appeared in the city directory as "Conversationalist," a reference to his role as Serbian language instructor for a group of U.S. soldiers being trained at the University of Pittsburgh as candidates for the Office of Strategic Services. While at St. Sava's, Father Nikolaj was separated from the Serbian Orthodox Church in 1942 when he broke his vow as a celibate priest by marrying Zora Strain. A petition was signed by parishioners asking for his reinstatement but it was all to no avail.
