Jean-Claude Pressac

Jean-Claude Pressac was a French pharmacist by profession, who became a published authority on the Auschwitz concentration camp homicidal gas chambers deployed during the Holocaust in World War II. He was the author of the 1989 book Auschwitz: Technique and operation of the gas chambers among other publications on the subject, which demonstrated the technical possibility of mass killing by gas chambers during the Holocaust, thus debunking many falsehoods promoted by Holocaust deniers. (Wikipedia)