Arapahoe County Sheriff Grayson Robinson speaks at a briefing on Saturday, Dec. 14, 2013, at Arapahoe High School in Centennial, Colo., where 18-year-old suspect Karl Pierson allegedly shot a student on Friday and then turned the gun on himself. (AP Photo/Ed Andrieski)

Photo by: Ed Andrieski

Arapahoe County Sheriff Grayson Robinson speaks at a briefing on Saturday, Dec. 14, 2013, at Arapahoe High School in Centennial, Colo., where 18-year-old suspect Karl Pierson allegedly shot a student on Friday and then turned the gun on himself. (AP Photo/Ed Andrieski)