NEWTOWN, Conn. (AP) — First, he killed his mother. Nancy Lanza's body was found later at their home on Yoganda Street in Newtown — after the carnage at Sandy Hook Elementary School; after a quiet New England town was scarred forever by unthinkable tragedy; after a nation seemingly inured to violence found itself stunned by the slaughter of innocents. Nobody knows why 20-year-old Adam Lanza killed his mother, why he then took her guns to the school and murdered 20 children and six adults.