The shop assistant
It was about five minutes before closing time. There were only two customers: a smartly-dressed woman and a teenage boy. The boy asked me to help him. He was looking for Alien. He wanted me to find it for him. I had to leave my desk and go into the back of the shop. I didn't really see what happened, but the shop manager suddenly came out of her office. She told me to lock the front door and to call the police. She was holding the boy by the arm. She warned him not to move. The police arrived a few minutes later.