That reference to Zylclon-B canisters along with evil did remind me of a documentary that NHK did on Zyclon-B story along with how evil it was. I recalled I thought that was perhaps the most evil stunt I have yet heard of by people who would not have been deemed crazy.
Sonderkommando - Jewish slaves of the SS who had to escort fellow Jews to the gas chambers.
I think Adolph Eichmann was the one who dreamed up the procedures to implement the ideas of Hitler. He would not likely fit a conventional description of being a psycho.