Go inside the investigation into one of the worst school shooting massacres in U.S. history.
No clear motive was spelled out in the 44-page summary of the investigation into last year's massacre at Sandy Hook Elementary School that was released Monday. However, new photographs of the scene -- and shooter Adam Lanza's home -- were released. Here is a sampling:
On the morning of April 19, 1995 Timothy McVeigh killed 168 people during the Oklahoma City bombing. Find out more about that tragedy here.