We, the Accused
In a 1963 interview with Peter Bogdanovich, Hitchcock talked about several unfilmed projects, including We, the Accused which was based on the Dr. Crippen case:
This was the story of a man who murdered his wife, ran off with his secretary, and was arrested on board ship, in about 1910. It is almost the definitive case of murder, trial and execution. It would be a very long picture, with detailed characterization, but I'm afraid it's terribly downbeat — and the man is middle-aged — so it wouldn't be very commercial. And you would have to spend some money on it.