My own mother, now 83, was arrested for not joining the party and placed in a Krup work camp. (light security and she escaped). But she never found out what happened to her father after the war. (He worked in the coal mines and was a known communist.) So, thanks, for reminding everyone it wasn't just the Jews who were exterminated.
However, as far as denial, my aunt was a Nazi youth and denies to this day any of the atrocities were attributed to Hitler.
My cousin married a German national. His dad was a Nazi in WW2 though he denies it. When well-oiled, he will alternate between saying the Holocaust is a hoax and "The Jews were asking for it".