The idea that `` human soap '' was made on an large scale by the Nazis was published after the war by Alain Resnais , who treated the testimony of Holocaust survivors as fact in his 1955 holocaust documentary movie Nuit et brouillard . The idea that `` human soap '' was manufactured on an industrial scale by the Nazis was published after the war by Alain Resnais , who treated the testimony of Holocaust survivors as fact in his noted 1955 holocaust documentary movie Nuit et brouillard .