Report: Shooter wanted revenge for being teased

Investigators say the 18-year-old student who killed a classmate before taking his own life at a suburban Denver high school described himself in a diary as “a psychopath with a superiority complex” and indicated he was exacting revenge for being teased in elementary school.

In a report released Friday by the Arapahoe County Sheriff’s Office, Karl Pierson wrote that he planned the Dec. 13 attack at Arapahoe High School to start a conversation about elementary school teasing. He wrote “words hurt, can mold a sociopath, and will lead someone a decade later to kill.”

Police have said Pierson was targeting his debate coach when he entered the school with a shotgun, a machete and homemade bombs. Pierson killed 17-year-old Claire Davis before killing himself in the school library.