The Glass Web (1953)

A television writer is blackmailed by a co-worker with whom he is having an affair. When he arrives at her house to have it out with her, he discovers that she has been murdered. He becomes the prime suspect while the real killer -- another fellow co-worker who had been being blackmailed by the victim -- begins to fabricate evidence against him. But when the writer discovers who the real killer is he uses the media to catch the true murderer.