Uncredited Cast Members

Are there any movie buffs who can identify the uncredited cast members in this film? It's strange that IMDB apparently does not have this information when so many film listings even vintage ones have information on the unbilled cast members. Who played the mother and brother of the first victim? The family and employees of the second? The blonde showgirl? The old man who guarded the cemetery?

I believe one of the IMDB reviewers is correct in stating Richard Martin, later well-known for playing Tim Holt's hispanic sidekick in a string of "B" westerns, is the unbilled boyfriend of the second victim.