There had been a 1956 film of that case starring Teresa Wright (who Hitch had directed in "Shadow of a Doubt" in 1943). Phyllis Thaxter, by the way, must be an incredibly brave and resouceful woman: after over a decade of acting on Broadway and in movies, she was struck by poliomyelitis in 1952 and was able, by dint of her remarkable character, to completely rebuild her career. Tom Helmore, the hypnotist, was Madeleine's husband in "Vertigo" (possibly Hitchcock's masterpiece).
Lawrence Treat, who wrote the story, was one of the first writers to develop the police procedural genre.