>>8098598When the Soviets were exterminating ethnic minorities in Siberia and the Cambodian killing fields were happening, most of the time they just shot people once in the head or chopped their heads off.
Creating an entire complicated network of gas chambers using thousands of tons of commercially available delousing agent and then burning the bodies with more tons of coal than was possible to exist in Germany at the time is a bit too autistic, even for German engineers.