What caused Bob Ewell's death?
Bob Ewell dies as a result of being stabbed in the ribs with a kitchen knife. When Bob Ewell attacks Jem and Scout on their way home from the Maycomb Halloween festival, Boo Radley intervenes and ends up saving the children by fighting Bob Ewell. During the fight, Boo Radley apparently stabs Bob Ewell in the ribs with a kitchen knife, and Bob dies underneath the oak tree. After listening to Sheriff Tate describe how Bob Ewell fell on his own knife and died, Atticus disagrees and mentions that he believes his son was responsible for Bob's death. Sheriff Tate proceeds to argue with Atticus and indirectly tells him that Boo Radley saved Scout and Jem by stabbing Bob Ewell. However, Sheriff Tate understands that Boo is an extremely shy, reclusive man who would not benefit from being in the community's limelight. Sheriff Tate explains to Atticus that he refuses to cast Boo into the community's limelight by expounding upon his heroics and believes that it is easiest to say Bob Ewell fell on his own knife and died.
Bob Ewell died from a knife wound. The cause of death given by Heck Tate was that Bob Ewell fell on his knife. At first, Atticus thought that Jem had stabbed Bob Ewell. Atticus was prepared for his son to go to trial. Then Mr. Tate informed him that it was Boo Radley who killed Bob Ewell. This was when Mr. Tate decided that they should simply conclude that Bob Ewell fell on his knife. This would protect Boo Radley from going to trial for murder.
This did not sit well with Atticus. He felt that it was dishonest. Scout, however, understood. She agreed with Mr. Tate's decision to not place the blame on Boo Radley. When she thought of Boo, she thought of innocence. She knew he was just trying to save her and Jem's lives. She did not think it was fair for Boo to go to jail for what happened:
"Well, it'd be sort of like shootin' a mockingbird, wouldn't it?" (To Kill a Mockingbird, Chapter 31).