I think I have what you're looking for! I keep a little website where I do short 'reviews' of horror movies that I've seen and Chamber of Horrors (1940) sprung to mind. Heres what I had to say about it:

Fun little murder mystery about a guy who dies and leaves instructions for his fortune to be buried with him in a tomb protected by a door with 7 locks and keys. 6 of the keys are stolen while the 7th is sent to a woman who is then caught up in a murder plot etc etc.. Another old Monogram movie which is surprisingly beautiful to look at. Tons of atmosphere from cobweb covered crypts, dungeons full of rats and coffins, old gothic style houses with paintings with cutaway eyes so unseen killers can spy on people in a room, then kill them with a gun through a sliding panel in the wall. Really cool stuff here. The acting is good all around with the girl and her friend being very nice to look at and alot of fun as well. The print I saw had an awful soundtrack though which made keeping up with the plot hard as it was tough making out dialogue.

Its out on DVD from Roan and can be found for $7.50 at DVD Empire.