Hydrogen cyanide
The Nazis began using Zyklon B in extermination camps in early 1942 to murder prisoners during the Holocaust. Tesch was executed in 1946 for knowingly selling the product to the SS for use on humans. Hydrogen cyanide is now rarely used as a pesticide but still has industrial applications. Firms in several countries continue to produce Zyklon B under alternative brand names, including Detia-Degesch, the successor to Degesch, who renamed the product Cyanosil in 1974.