Saw "The Unsuspected" yesterday on TCM, a fabulous 1947 film with Claude Rains. But I'm thinking if another film that also used then-new technology in the plot (as Rains did with a record mastering device). This other plot revolves around a pianist/murderer who leaves a record playing in his locked study, while he pretends to be rehearsing, when he is actually murdering someone. Please help me identify this film! And where can I get a copy of "The Unsuspected?"
-- Brian Charles