While in prison, Unterweger wrote short stories, poems, plays, and an autobiography, Purgatory or The Trip to Prison – Report of a Guilty Man, that later served as the basis for a documentary.
Selama dalam penjara, Unterweger menulis cerita pendek, puisi, naskah drama, dan autobiografi, Purgatory or The Trip to Prison—Report of a Guilty Man, yang kemudian diadaptasi menjadi sebuah dokumenter.