What causes the lynch mob in front of the jail to disperse and go home? (book name - To Kill a Mockingbird ) Boo Radley appears with bloody scissors, screaming and lunging at the mob. They flee out of fear for their lives. Sheriff Heck Tate shows up with his deputies and orders the mob to disperse. They do so because they don't want to get in trouble with the law. Scout recognizes Mr. Cunningham and talks to him about his son, Walter, and his entailment. This makes Mr. Cunningham realize that he is not just part of a mob, but he is an individual and Atticus is his friend. Atticus reasons with the mob and convinces them that lynching Tom Robinson would be wrong. They go home because Atticus's logic has convinced them that it is best to let the court decide Robinson's fate.