Boo Radley lived with his father in the Radley Place. When he was 33 years old, he was cutting out newspaper articles for his scrapbook when he suddenly stabbed the scissors into his father's leg.
He went to prison for some time, and the police almost sent him to an insane assylum, but at the end he returned to the Radley Place.
When Boo's father died, Boo's older brother Nathan moved in to take over. Nobody has seen Boo ever since. Now neighborhood kids avoid the house at all costs. Rumor has it that Boo leaves at night and stalks around the neighborhood, but no one has ever actually seen him.