What story do Heck Tate and Atticus decide on as far as what happened to Bob Ewell?

In the novel "To Kill a Mockingbird" by Harper Lee, Heck Tate and Atticus Finch come to an agreement about the events surrounding Bob Ewell's death. They decide to present the story that Bob Ewell fell on his own knife and died accidentally during his attack on Jem and Scout Finch. This version of the story is fabricated to protect the person responsible for Bob Ewell's death, Boo Radley.