I found this article by the US Holocaust memorial museum. So not some runt of the street. it is talking about freemasons murdered by the Nazis, and gives numbers of up to 200k people.
Now I thought that freemasonry for long didn't exist anymore in the 1930ies, and that it was some kind of elitist society. 200.000 people is nether secretive, nor very elitary.
Can anyone give me some historical context etc. I just read this the first time and it feels kinda weird.
the article: http://www.ushmm.org/wlc/en/article.php?ModuleId=10007187
Freemasonry is not an elite fraternity at all. Anyone can join (just have to ask, and then there's an interview process and someone volunteers to vouch for you).
200k is a very high estimate. Masonic scholars place the number in the tens to low hundred thousand range, but yes, many German Masonic Lodges were raided, their records seized and their membership detailed and eventually sent to concentration camps as political prisoners (the same classification, interestingly, as was often used for lesbians).