He was involved as a member of the Sicherheitsdienst (SD) in the guarding of prisoners at Auschwitz concentration camp and the Holocaust in Yugoslavia.
Egner was on the List of Most Wanted Nazi War Criminals of the Simon Wiesenthal Center.
Egner served in an Einsatzgruppe, a majority of whose members were Volksdeutsche, during the Nazi occupation of Yugoslavia.
[3] Documents show that Egner, as a Wachmann (guard), escorted a train of Sinti and Roma men, women and children to Auschwitz.
[4] Serbia checked Egner's role in executions at Avala and Judenlager Semlin and issued an international arrest warrant.