Leitner was elected president of the Orthodox Jewish congregation of Oradea in December 1941, succeeding his mentor István Ullmann, who died in labour service.
In his diary-like memoir written many years after the events, Leitner recalled that the crematoria, the concentration camps and the mass murders were also discussed during the meeting.
Leitner and his colleagues established a housing department, which managed the removal of Jews from their apartments, the proper assignment of the vacated properties for German and Hungarian needs and the moving of different relatives and families together.
[1] In his diary, Leitner noted in an ironic tone that "there was an equalization between the [social] classes that no socialist scientist could ever even dream of" in the main ghetto.
In Nagyvárad, the gendarmes commanded by lieutenant-colonel Jenő Péterffy, were especially sadistic in their searches for valuables, which took place right by the ghetto in the Dreher brewery.
1924) were allowed to board the so-called Kastner train and, through Bergen-Belsen, leave for Switzerland in late June 1944, because of Leitner's former activity in the Zionist movement.