Yes, Adolf Eichmann, not Albert. It’s been a long week.
But Kastner was a collaborator. Eichmann himself, in a 1950s interview with a German magazine (that was later republished in Life Magazine) before he was caught, bragged that without Kastner he wouldn’t have been able to kill so many Hungarian Jews. Kastner knew beforehand, unlike the rest of Hungarian Jewry, of Eichmann’s plan to send Hungarian Jews to death in Aushwitz. Kastner never told his fellow Jews and instead let Eichmann round them up without them resisting or trying to run away (as anyone knowing they’re being shipped on trains to death camps would try to do), in order so that Kastner could get one trainload of people saved, who mostly were his family and colleagues.
Read the Vrba-Wetzler Report. Even the zionists courts in Israel admitted that even after the war Kastner defended Nazis in the Nuremberg Trials.