Lt. J. Paul Vance of the Connecticut State Police conducts a news briefing, Saturday, Dec. 15, 2012 in Newtown, Conn. The massacre of 26 children and adults at Sandy Hook Elementary school elicited ... more 

Lt. J. Paul Vance of the Connecticut State Police conducts a news briefing, Saturday, Dec. 15, 2012 in Newtown, Conn. The massacre of 26 children and adults at Sandy Hook Elementary school elicited horror and soul-searching around the world even as it raised more basic questions about why the gunman, 20-year-old Adam Lanza, would have been driven to such a crime and how he chose his victims. (AP Photo/Jason DeCrow) less