1.17. A man is found shot to death in the front seat of his car; a gun lies out of his reach in the back seat. All the windows are closed and the doors are locked; there are no bullet holes anywhere in the car. (SP, from The Next Book of OMNI Games; partial AC wording)
1.17 answer: The car is a convertible; the top was down. (Or the sunroof, or something else that's neither window nor door.) The murderer shot him and then dropped the gun into the back seat of the car.