Why were some of the Nazi "Doctors" that performed experiments on humans released?

I was reading about the horrible crimes committed by Nazi "doctors" at concentration camps during the 3rd Reich, and i noticed that on the page that showed there "fate" it said a number of them were realized after as little as 10 years, some led normal lives, even took up medical practice! How is this possible, its ridiculous, some of them them were straight up executed but others were released, why was this?