2. Dr. Sigmund Rascher
Rascher was a very important scientist during the Nazi use of concentration camps during the World War II. Some of his infamous experiments at Dachau concentration camp included hypothermia research in which three hundred people were used in the experiment against their will.
They were subjected to high-altitude, malaria and other medication experiments during which a third of them died. He also developed standard cyanide capsules which could be easily consumed either intentionally or accidentally.
Surprisingly, this was the means through which one of his closest friends committed suicide.