The Florentine Dagger [1935] [DVD]

Juan Cesare, a descendant of the Borgia's of Vienna, thinks he may have a murder streak in him acquired from his long-dead relatives, is is love with Florence Ballau, but her father lodges a strong protest. Papa Ballau is later found dead with a Florentine dagger of the Borgia type stuck firmly in him. Juan is all wrought up and tortured by thoughts he may have been the killer. But there is also a disfigured housekeeper on the premises who may or may not have had a motive.

Here is a review from imdb:

Based on a novel by Ben Hecht, THE FLORENTINE DAGGER is raised above the level of modest murder programmers on the strength of its unusual plot, moody atmospherics and very fine acting. Sir C. Aubrey Smith graces the proceedings as a kindly old doctor who helps a young playwright and a spirited actress (Donald Woods & Margaret Lindsay) find happiness together, despite homicide and a possible family curse. Robert Barrat is also much fun as an eccentric, flirtatious police inspector; surprisingly, he becomes the story's true hero in the movie's closing moments. The supporting cast includes Henry O'Neill as a Viennese theatrical producer; Florence Fair as his troubled housekeeper; Frank Reicher as a harried stage manager; Rafaela Ottiano & Charles Judels as worried Italian innkeepers; Paul Porcasi as a timid policeman; Eily Malyon as a lady who knows more about the murder than she's willing to say; and wonderful Herman Bing as a flustered Austrian baker.