Why were no autopsy's done on the Holocaust victims?

Industrial killing requires industrial body disposal. There wouldn't be many ged bodies to autopsy. The Nazis killed all sort of non -jewish people too, like people aiding jews, cripples, s, communists, etc. Also many of the 'jews' were not practicing jews, the Nazi's treated them as a race, not caring about whether or not they were practicing jews. So a large proportion of that number were just people who's parents were jews. Or had jewish heritage, but were not necessarily jewish in the sense we mean today.