Complex sentence: He goes crazy toward the end of the story, admitting to being a former Nazi doctor at Buchenwald, where he worked in a program focused on experimentally-induced insanity to render Jews permanently catatonic.
Split into simpler sentences: He goes crazy toward the end of the story. Admitting to being a former Nazi doctor at Buchenwald where he worked in a program focused on experimentally-induced insanity to render Jews permanently catatonic.