Did the Germans know that people were being, incarcerated, deprived, assaulted and even executed by the authorities with out due process? Probably but then did Americans know about Guantanamo and extraordinary rendition? I don't mean to pick on Americans. The American response to 9/11 was a normal and utterly predictable human group response to threat and attack. When groups of human perceive themselves as under threat and attack, their concern for out groups drops precipitously.
My Dad was attacked (verbally and nearly physically) by a group of German women, when he was a POW in WWII. "How can you do this? How can you do this?" they screamed at him, referring to the allied bombing. When he told me that story I felt strong anger against those women. "What about the bombing of Warsaw, Rotterdam Coventry?" I thought. But of course that's not how most people work. Humans find it very easy to experience themselves as victims. And when people experience themselves under severe attack, their in group identification ramps up massively. I watched the London tube bombings (on the tv) with my girl friend of the time. She was a left wing progressive anti war English graduate, who thought 9/11 might have been an inside job. I watched her morph (temporarily) into a pro war nationalist in front of my eyes. This is what happens, progressives become ethno nationalists and concern for out groups plummets.
Given that Germany in the nineteen thirties was by modern standards a middle income country, given the low percentage, by modern standards of post 18 education. Given what the German people had been through: WW1, the blockade and hunger, the revolution, the hyper inflation, the 6 million unemployed, the start of the second world war and a new blockade and then from 1940 an increasing bombing campaign its remarkable that Germans showed as much concern as they did for the fate of out groups.