Who is Mr.Radley from To Kill a Mockingbird?

He is their next door neighbour, or he lives somewhere on their street. But im pretty sure its next door. There is a Mr Radley, but i think he dies and the other Mr Radley is his son, called Boo. He was caught when he was a teenager, and the police or whatever told Mr Radley they were gonna take him to like Juvy, so Mr radley said he'd keep him at home, and he's only been seen like a couple of times since. He's like the boogie man to kids.