Who set out to kill the members of the church? On April 27, 2003, in the hamlet of New Sweden, Maine, Walter Morrill was sipping coffee in the fellowship hall of the Gustaf Adolph Lutheran Church. Within 12 hours, the kindly old man was dead. Fifteen other members of the congregation fell gravely ill. Ruled a homicide, the largest criminal arsenic poisoning in U.S. history spread whispers of fear through this peaceful town. Which one of their close...