Kelly`s dad&John`s mum re couple, they were driving and the car got bad on the way. The man decided to look for help at a Filling Station. He made sure nobody was in the car, He rolled all the windows up,&locked all of the sedan's doors before leaving,but when he came back,his wife was dead,and there was a stranger in the car.No physical damage was done to the car,so how did the stranger get in?(riddle)