A man kills his wife with a knife in their car when nobody is around to see. Then he throws her body out of the car and is careful not to leave any fingerprints on her. He throws the knife into the ocean where it will never be found and goes home. Two hours later the police call him and tell him that his wife has been murdered and that he needs to come to the scene of the crime as soon as possible. When he arrives they arrest him. How did they know he murdered his wife? I also tell me in the comments and I may give you