Nazi doctors also did experiments on prisoners at Buchenwald. For example, in 1942 and 1943, they used 729 prisoners to test a vaccine for typhus. This meant the prisoners were given the vaccine, and then given typhus on purpose. 154 of these prisoners died. In another experiment, Nazi doctors wanted to see how much of a certain poison was needed to kill a person. They gave four Russian POWs the poison. When the POWs did not die, they were "strangled in the crematorium" and then "dissected" (cut apart to study their bodies). Doctors also burned other prisoners very badly with white phosphorus to test whether a medicine would help similar wounds caused by bombs. After the war ended, at the Nuremberg Trials, one of these doctors defended himself by saying that while he was a doctor, he was also a "legally appointed executioner" (meaning the law allowed him to kill people).