La Donna Bianca is an early giallo based on the stage play The Letter by William Somerset Maugham – the play appears to be full of intrigue and drama based on the brief synopsis I’ve read online.
I will expand this post soon – in the meantime, once again I’m surprised by what you can dig up with a few simple web searches. There isn’t much info on director Jack Salvatori beyond a date of birth, his rather modest filmography, and short biography on his Italian Wikipedia entry. So it was a pleasant surprise to find his son’s memories of his father online – link HERE (off-site backup HERE)
Maugham’s The Letter must have been quite popular at the time because it had also been filmed 2 years earlier in America as a Paramount production. You can find an HD copy on YouTube – the film is officially in the public domain.