Because Atticus embarrassed Bob and Mayella Ewell in the courtroom trial of Tom Robinson, Ewell attempted to get back at Atticus by harming Scout and Jem. It was a cowardly thing to do, but luckily, the bravery of Boo saved the kids. Atticus decided to go along with Heck Tate's story about Bob Ewell falling on his knife to protect Boo Radley. Boo had just saved Scout's life, and to Atticus and Heck Tate, Boo's life had been hard enough without answering questions or being arrested or prosecuted for the death of Bob Ewell. Boo was an innocent who symbolized a mockingbird in the book. Mockingbirds don't do harm, and therefore, should be protected. Boo was a kind, gentle soul who had hardships to bear because of his family. The publicity of the death would probably have caused a lot of anguish and problems for Boo who had been kept hidden away for years in the Radley house. Atticus and Heck Tate realized that what happened to Bob Ewell was justice in a sense. His evil, racist accusations about Tom Robinson were unjust. His attempt at revenge towards Atticus showed what a horrible, violent person he really was. In addition, neither Atticus nor Heck Tate wanted to put Maycomb through another trial involving innocent people.