...this was inspired in part by Theodore Dreiser's "An American Tragedy", which came out in 1925 and was in turn based on the Chester Gillette- Grace Brown murder of 1906. Dreiser's book was done as a 1931 sound film and redone as "A Place in the Sun" in 1951. Neither is as good as "Sunrise", however.
http://en.wikipedia.org/wiki/An_American_Tragedy
It was based on a story by Hermann Sudermann entitled Die Reise Nach Tilsit (A Trip To Tilsit). I doubt if Dreiser's book had too much to do with it. Murnau's screenwriter/scenarist was also German, Carl Mayer. The original story is different in many ways, but there was a boat scene where the man decides not to drown his wife.
share....I think it's possible. The actual murder case had international coverage. Recently, critics even compared Woody Allen's "Match Point" to Dreiser's novel. What I found amusing was the weapon in the actual murder wasn't a boat oar, as one would assume, but a tennis racket.