Clown

Riddle: A boy's parents went out to eat. They said to the boy "We will be home around 12:00 (AM)". The boy got into bed at 8:00 and tried to go to sleep. He woke up for some reason at 10:00 and he saw a clown standing right out of his window. Home got really scared so he just got back into bed. He woke up at 12:00 and the clown was standing there with a knife in his hand. The parents got home at 12:15 and they went into his room and his head was chopped off with a knife in his head. They parents were so mad!! So they asked the elevator operator (they lived in an apartment) if they had seen anyone go in or out of the elevator. And he said. " I did see someone go out but not in of the elevator he was wearing a clown costume too. They asked the doorman if he had seen anyone go in or out of the door and he said "I did see someone go out, but not in. He was wearing a clown costume too. The boy's window was 20 stories up. How is it possible that the clown got in his room to kill the boy?