A Tragedy at Midnight (1942)

This Republic murder mystery starts with a radio broadcast by Greg Sherman who solves cases on the air that the local police cannot solve. As he names the perpetrator of a recent murder we see the criminal, who is listening to the show, become alarmed and start to make his escape. The scene shifts to the police department where the chief, fearing for his job, assigns officers to get something, anything, on Sherman and get him off the air. Meanwhile, Greg and his pretty wife Beth are parting company. He's going to a party and she's going to visit her pregnant sister in the hospital. The next morning Greg wakes up and nudges his sleeping wife. When she doesn't respond, he pulls off the covers and finds not his wife but a strange woman, dead and with the murder knife still sticking up out of her back. While he's still recovering from the shock, Beth walks into the bedroom. Thinking that she has discovered her husband with another woman, she leaves and calls the police. The police are delighted of course, but Greg escapes as they are arresting him. Now he must solve the mystery by himself...