During his visit on Shutter Island Marshal Teddy Daniels repeatedly has traumatic memories of the liberation of the KZ Dachau during his service in WWII, where he saw the piles of corpses, let an officer die slowly after a failed suicide attempt and ultimately shot the guards with his fellow soldiers. He even thinks to remember Dr. Naehring as one of the doctors from the KZ, yet this accusation is rather ignored by everyone, including Teddy, while a former war criminal working as a doctor in a U.S. asylum would indeed be a big scandal.
But of course, as we learn at the end, Teddy is an unreliable narrator and the whole investigation was a staging to cure Andrew Laeddis from the alternate reality he invented to suppress his guilt in his family's death. At one point Dr. Cawley even says "You really were at the liberation of Dachau, but probably didn't kill any guards there". So I wonder, to which degree were his memories of Dachau really Andrew's memories and to which degree were they just part of Teddy's false reality and what is their further meaning? If they were all just made up by him, how do they relate to the rest of the story, or were they just supposed to be a distraction for the audience, giving the conspiracy-laden and disturbing Teddy-reality yet another strange angle?