there's an old short story named "The tell-tale heart" where a paranoid schizophrenic man kills an old man who he was close to, because apparently the old man had a "vulture eye"; the story is just him lying to the cops and saying he's not crazy. But he keeps hearing the old man's heartbeat because he's guilty so at the end, just when he's almost convinced the cops that he's innocent, he turns around and confesses.