experience.
This was in the 70's, long before mobile phones. Her waitress co-worker got off work after midnight, and started driving home. She immediately noticed a car following her with its bright headlights on the whole way. As she arrived home, the car followed her into the driveway with its bright lights still on. She ran into the house and called 911. When the police arrived, the car was still sitting there with its bright lights on. The driver of that car had seen a man get into the back seat of the lady's car, and thought it was best to keep shining a bright light on the back. The police found the man in the back seat, with a knife.