@Ionus,
That isn't unknown to me. But I have never heard of any kapo running a concentration camp. And I don't know if they were Nazis.
However, kapos were "functionaries" only within their group - thus giving the camps a second hierachy.
Usually, kapos were what is called below "Berufsverbrecher" (professional criminals), who were in all groups
I don't have access from here to some specialized sources - I don't think that (former) Nazis were in concentration camps but in some other prisons. I can be wrong.