The witness of the title is Barbara Stanwyck, who insists she's seen a man strangling a girl in the apartment across the street. The murderer is George Sanders, an ex-Nazi with plenty of experience in covering his tracks. Deftly disposing of body and clues, Sanders is able to convince the authorities that Stanwyck is hallucinating. But Stanwyck persists, forcing Sanders to show his hand in a fateful climax. Witness to Murder is far beneath the talents of its stars, though both Stanwyck and Sanders, pros that they are, give the material the old "Academy Award" treatment.
~ Hal Erickson, All Movie Guide