I think it is in Robert Fisk's Pity The Nation: Lebanon at War that an odd feature of the Armenian genocide is mentioned. Ottoman Turkey was at the time an ally of the German Empire, and there were a large number of German troops stationed in the Turkish Empire to assist their allies. Fisk wonders if any junior officers lent a helping hand to the elimination of the Armenians from Eastern Anatolia, coming home with some top tips they could apply in Europe just under 30 years later.
One German officer who was in Turkey at the time was Armin T. Wegner. Rather than assist in the extermination of the Armenians, he did his utmost to prevent further massacres and worked tirelessly to publicise the horrors that Enver Pasha's government was perpetrating. As well as collecting and disseminating documents on the massacres, Wegner took numerous photos of Armenian deportees and of the corpses of the genocide's victims; if you have seen any black and white pictures of corpses or desperate Armenians in the media over the last few days, they were almost certainly taken by him.
Wegner lived until the late 1970s, though he did spend some time in concentration camps during the Third Reich period. He was apparently the only German writer to publicly denounce anti-Jewish measures introduced by the Nazis in 1933.
You can see some of Wegner's pictures here: Armenian Deportees: 1915-1916