Hi, the part of our FAQ dealing with human experimentation by Nazis has some great answers on this by a variety of different writers including /u/commiespaceinvader, /u/estherke and /u/400-rabbits.

(That's hillsonghoods's reply the last time this was asked. I did a search for "Mengele" in the search box at upper right on the Web interface. I'd /u them too, but I'm told that Reddit won't ping people if there are more than 3 /u's in a comment.)