Simon & Simon (1981) : 8x12

Rick and AJ are asked by Tom Huntley, a State Senatorial candidate, to find out whether his wife Colleen is having an affair. Despite their rule against working on cases involving marital difficulties, they agree. Naturally, it's all a setup. The Simons are put in place as witnesses to the apparent murder of Mrs. Huntley. They report the murder and turn over the pictures they've taken to the police. After her body turns up, they realize that what they saw was a scripted scene played out between two hired actors.