Arizona prison officials have revived a decades-old gas chamber and are planning to use hydrogen cyanide — the same deadly gas used by Nazis at Auschwitz and other extermination camps — to kill people on death row. That’s according to documents obtained by The Guardian, which show Arizona’s Department of Corrections spent over $2,000 buying ingredients for the gas. The department has also “refurbished” a gas chamber at a prison in the town of Florence that was built in 1949 and hadn’t been used in over two decades.