Karl Pierson, 18, went on the shooting rampage on Dec. 13 at Arapahoe County High School in the southern suburb of Centennial.
He shot and killed himself as sheriff's Deputy James Englert, who is assigned as a resource officer at the school, closed in on him.
According to investigators, Pierson was carrying a shotgun, more than 125 shotgun shells, a machete and three homemade firebombs.
Claire Davis, a 17-year-old senior, was shot in the face. She died a week later from her injuries. Authorities have said Davis was a random victim and that Pierson's main target was a speech team coach who had disciplined him.
The Associated Press contributed to this report.