In the story, he said that he heard many things in hell so that kinda shows that he's strange in a way and he watched the old man sleep just so he can kill him.
Explanation:
He says heard things in heaven and hell and when he killed the old man he actually planned out how he was going to kill him and then he hid the body in the old man's room i think and then when the cops came because of a noise complain of the neighbor. Edgar said that he heard the old man's heart beating. Hoped I helped!
