Still, there seems to be no evidence that he was a Nazi. My country was also under the control of a fascist party during that time, yet it was a conspiracy of soldiers and low-rank officers that brought it down.
Beware imprecise language: Germany has not had a Nazi state since 1945, and is not anything like that. Also, there were SS officers and German military officers, and they were not the same.
All the more reason that calling this guy a Nazi interrogator is useful and reasonably correct! If you called him a German interrogator you'd have no idea what era he from or what role he might have played. The phrase "Nazi interrogator" tells us immediately that he was an interrogator for the German government somewhere between 1933 and 1945.
My point was not to defend those working for the Nazis, but you say "[Nazi] is that country's defining characteristic" in your comment, and that has to be 'was' at the very most. You're carelessly suggesting that Germany still is defined by Nazism, hence the suggested correction.
Sorry if I wasn't clear. By "that country" I was specifically referring to Nazi Germany. Modern Germany, having been through occupation, division and reunification, with no continuity in the state, a different constitution, and different borders, is not really the same country.
You can be like Humpty Dumpty and use the word like that if you want, but it seems like highly unhelpful terminology to me and rather insulting to the people concerned.
If you want an example of something that really is Nazi, take a look at the downvoting that's going on here! (That was an attempt at humour; downvote it.)
It seems extremely helpful to me. It immediately tells us that this guy was active somewhere between 1933 and 1945 and not, say, an interrogator of Cold War spies in the 1970s, or someone who worked under an 18th century Prussian king or whatever. It also immediately emphasizes the contrast between "the value of kindness" and the culture brutality that would have been all around him.
Maybe he wasn't actually a member of the NSDAP but if you insist on reading "Nazi interrogator" as implying party membership, I would suggest it is you who are insisting on a weird and unhelpful meaning.
Scharff is normally described as a Luftwaffe interrogator, which not only tells you "this guy was active somewhere between 1933 and 1945", but also "immediately emphasizes the contrast between "the value of kindness" and the culture brutality that would have been all around him" and even in which part of the military forces he worked, which is even more valuable (i.e. Luftwaffe, not SS or Gestapo). Finally it does imply NSDAP membership, and indeed Scharff was never a party member and is unlikely to be a Nazi of conviction.
“Luftwaffe” is also the name of the modern German Air Force created in 1956. If in fact that term conveys the correct time period to the reader, it is only by luck and ignorance.
While "Luftwaffe" alone does not reveal much about the timeframe, "Luftwaffe interrogator" gives a strong clue. The need for air force interrogators likely decreased a lot since WWII for a country like Germany