True Confession (1937)

Helen and Ken are a strange couple: She is a pathological liar; he is a scrupulously honest (therefore unsuccessful) lawyer. Helen starts a new job, and when her employer is found dead, all the (circumstantial) evidence points to her. She is put on trial for murder, and her husband defends her. He thinks she is lying again when she says she didn't do it, and insists she should plead that she did, but in self-defense. Charlie, a shady, odd character who may or may not know something about what really happened, hangs around the courtroom and jail, making rude comments and noises. After Helen is acquitted, he tries to blackmail them.