A man murders his wife with a knife in their car. Nobody is around to see this.

He throws her out of the car being careful not to leave any fingerprints on her body.

Next he throws the knife off a cliff into a gorge where it will never be found and he goes home.

And hour later the police call him and tell him that his wife has been murdered and he needs to come to the scene of the crime immediately.

As soon as he arrives he is arrested.

How did they know he did it?

Answer:

He never asked the cop where the scene of the crime was, so they knew he had murdered his wife.

Taken From: 9GAG