They were among the best of us, and their alleged killer, Dylann Roof, one of the worst. He sat beside them throughout the session of religious study before gunning them down. Apparently, this was not a spur-of-the-moment act. Acquaintances say Mr. Roof had expressed deep anger toward black people and had boasted, as long as a month ago, about his intention to spark a race war. As he shot and reloaded and shot some more at the church on Wednesday night, he responded to pleas of mercy by saying he had to kill because, "You rape our women, and you're taking over our country -- and you have to go."