 As his successor he opted for his long-time colleague Hans Drexler who had been an active supporter of the Nazi party.Drexler would later write Kroll's obituary in the "Gnomon", apologising for his predecessor's alleged ″lack of a positive world view″.While not being a victim of the Nuremberg Laws himself, Kroll witnessed the removal of his colleagues from office and the persecution of his former pupils, some of whom he aided in finding work abroad.