An American missionary couple who were allegedly attacked by drug prohibition gunmen in a dangerous part of Mexico may have been targeted for their expensive pickup truck, because drug gangs covet the vehicles, police said. Sam Davis told investigators that that he and his wife were driving near the city of San Fernando, about 70 miles south of the Mexican border city of Reynosa, when gunmen in a pickup truck tried to stop them. When the Davises sped up, the gunmen fired, shooting Nancy Davis in the head.