Who is Chip Carnes from Under the Banner of Heaven: A Story of Violent Faith and what is their importance?

Chip Carnes is drifter. He joined the Lafferty brothers on their trip before Brenda and Erica Lafferty were murdered. He joins the group after his car breaks down, and he doesn't have enough money for the repairs. Carnes is the only member of the group to tell a different story about the murders. In court, he testifies that Ron killed Brenda while Dan killed the baby. Note, Carnes testimony was a direct result of being threatened with the death sentence if he didn't provide evidence that would help get a first degree murder conviction for both of the Lafferty brothers.