The kapitän was a member of the Nazi party who had impregnated the Brigitte character which B'Elanna Torres was playing. A brutal man and very much believing in Adolf Hitler's ideals that Germans are the "master race" and having "pure blood", causing Karr to criticize him for "underestimating his prey". He was in charge of a province in France. He was ultimately killed by Klingons, who were part of another simulated hunt scenario, in the final battle for the town. (VOY: "The Killing Game", "The Killing Game, Part II")
In billing the SS officer as "Kapitän", the composers of the credit roll had, historically at least, made a double error in one; Kapitän actually refers to a naval captain in both the German military (Kriegsmarine, the German navy), as well as its merchant marine. Since he was an SS officer, the correct rank would have been "Hauptsturmführer" – factually wearing the correct rank insignia – or at the very least "Hauptmann" to reflect the regular German Wehrmacht army branch. He was actually called "Hauptmann" in dialog once, by the Brigitte character in Part I, when she comes visiting him for the first time.