The Streets of San Francisco S02E21 - The Hard Breed

Two "Gunsmoke" writers teamed on this modern-day Western set at a rodeo in San Francisco's Cow Palace. A bronc rider dies in what appears to be an accident. A rodeo clown looks around the scene after the police leave and discovers the rider's rope -- which was cut almost halfway through before it broke, leaving the bronc free to throw him. The police come back to investigate the scene, and before long the chief suspect is also murdered in another "accident."