A man Is sitting in his car all the windows are up and the doors are locked there is no one in the car with him, the keys are in the ignition and the man has been shot in the back of the head there are no holes in the car or windows from a bullet the doors could only be locked from the inside while the keys are in the car so the killer did not lock the car.also he did not shoot himself.there is no gun in the car.
How did he get shot?