S7E25: In Cold Blood / Red Handed

A grandfather hears a knock on his door, little does he know that a killer stands on the other side of it. The suspect flees the scene and crashes his car just down the road. Will the car be the key to identifying the killer? In a bedroom and elderly man lies dead, his killer strangled him. Is the strange man people saw knocking on doors the killer? Can detectives identify him and find him in time?