Starting from Joe's link, I'd recommend people to go one click further to: "Who was Martin Niemoller"

Also this gives an eye-witness accoutn of his arrest.

In addition I find there was an "award winning (cinema) documentary of his life" made in 1985.

However, like Wolfgang I can't find a German text of the words. And I've found three different attributions of when they were uttered; perhaps the most likely is that they were made in 1945 on Niemoller's release from concentration camp. (Which would put them later than his autobiography . . . )

G.