Hydrogen Cyanide was used in the 1800s as a pesticide for agricultural purposes by California orange grower. The Holocaust started in 1933 where millions of Jews were killed by the Nazi’s. In early September 1941 the main camp Auschwitz was experimented on by using the poison gas Zyklon B for mass extermination of human beings. There were equipped underground rooms for undressing and gas chambers disguised as shower rooms, the SS pushed around 2,000 prisoners at a time. The Nazis tricked the victims to carry out the mass killing with maximum efficiency, the SS instructed the suppliers to provide Zyklon B without the warning agent. Zyklon B was later replaced by potassium cyanide in the form of a salt, which turned into hydrogen cyanide when water was added to the compound. After the war the suppliers were brought to court with criminal trials because they took part in the of killing 6 million Jewish people.