Karl Halverson Pierson, the 18-year-old who opened fire at Colorado's Arapahoe High School yesterday before killing himself, was "really, really angry" after a problem he had with the coach of the debate team earlier this year, and multiple students tell the Los Angeles Times that's who he was targeting yesterday. Pierson was passionate about debate, but got in an argument with the coach about changes he wanted to make to the team in September and ended up kicked off the team and suspended from school after threatening the coach, says a debate team co-captain who asked Pierson to consider coming back on the team Monday. But Pierson said he still hated the coach and added, "Apparently you get suspended for threatening to kill a teacher."
The co-captain adds that Pierson may have been upset that the team just won first place in a tournament; Pierson had been the best debater on the team, according to the co-captain. Pierson was shouting the coach's name yesterday, found him, and "shot once and missed," another student says. The coach escaped and fled the school, and the sheriff tells NBC News that may have saved lives: It was "the most important tactical decision that could have been made," he says, because "maybe the threat went toward him rather than the school." As for the 15-year-old girl who was shot, who remains in critical condition, police say "there's no reason to believe she was a target." Friends say Pierson was smart, "slightly geeky," into politics and gun rights, and had friends, but was also bullied. "Only those that could cope with his personality became close with him," says one student. Another adds that Pierson seemed to change after his parents divorced recently. (Read more Karl Pierson stories.)