Under the Banner of Heaven

Under the Banner of Heaven: A Story of Violent Faith is a nonfiction book by author Jon Krakauer, first published in July 2003. He investigated and juxtaposed two histories: the origin and evolution of The Church of Jesus Christ of Latter-day Saints (LDS Church) and a modern double murder committed in the name of God by brothers Ron and Dan Lafferty, who subscribed to a fundamentalist version of Mormonism.

Source: Wikipedia — Under the Banner of Heaven (CC BY-SA 4.0)