What does Atticus say about Bob Ewell's guilt?

During Atticus' closing remarks he explains how Mayella felt guilty about breaking the "time-honored code" by seducing a black man. He mentions that her father, Bob Ewell, witnessed the encounter and elaborates on Bob's reaction. He says that they don't know for sure, "but there is circumstantial evidence to indicate that Mayella Ewell was beaten savagely by someone who led almost exclusively with his left." (Lee 272) He says that they do know Bob Ewell "swore out a warrant" that resulted in Tom Robinson's arrest. Atticus makes it clear to the jury that Bob Ewell witnessed Mayella physically interact with Tom Robinson and beat her shortly after. In 1930's Alabama, interracial relationships were viewed with contempt and was the reason Bob Ewell beat his daughter. Earlier in the trial, Atticus makes Bob write his signature. Bob's signature indicates that he is left-handed. When Tom Robinson is on the witness stand, the jury finds out that he has a crippled left arm. Mayella's injuries were predominately to the right side of her face, which suggests that a left-handed person beat her. This evidence infers that Bob Ewell beat his daughter. Atticus explains Bob's motivation to beat his daughter and claim Tom Robinson raped her. Bob was attempting to protect his family's integrity and cover up his brutal assault on his daughter.