Frailty (2001)

Wesley Doyle (Powers Boothe), the FBI agent heading the search for Texas' notorious "God's Hand" murderer, is understandably suspicious when a man walks into his office and announces that he knows the identity of the elusive serial killer. Introducing himself as Fenton Meiks (Matthew McConaughey), he claims that his brother, Adam, killed all those people and then killed himself. But Adam's crimes are just one part of a long and complex story that Meiks wants to share with Doyle so he will understand what motivated his brother to kill. Past and present converge as the two strangers drive together to the rose garden where Adam is buried and Meiks begins his tale of faith and retribution.