Police reveal shooter was 18-year-old senior

DENVER—Today’s giant Denver Post headline screamed one word: “Again.” Yesterday, an 18-year-old senior at Arapahoe High School in Centennial, Colo., entered the school with a shotgun, hunting for a teacher with whom he wanted to settle a score. The teacher fled, but the student opened fire, critically wounding a 15-year-old girl and ultimately killing himself. It was the fourth time in 14 years Coloradans have endured such a tragedy and happened the day before the one-year anniversary of the mass shooting at an elementary school in Newtown, Conn.

Authorities said Karl Pierson, a frequent winner on the school’s speech and debate team, went to classes the morning of the shooting. But at 12:30 p.m. MST he reentered the building brandishing a shotgun and went searching for a specific teacher, Tracy Murphy, the school librarian and debate team coach.

Joe Redmond, a senior at Arapahoe High and one of three co-captains of the debate team, told The Los Angeles Times Pierson was kicked off the debate team after a conflict with Murphy. Pierson then threatened to kill the teacher and received a several week suspension in September.

“When he came back, he was really, really angry,” Redmond told the Los Angeles Times. Pierson wanted to go to the U.S. Air Force Academy after he graduated from high school, and he believed the suspension on his record ruined his chances, Redmond explained in an interview with The New York Daily News.

Upon entering the school, Pierson repeatedly called out for Murphy and ran toward the school library, according to witnesses. Students and teachers reported hearing several shots in the hallway and scrambled to lock classroom doors, turn off lights, and hide out of view of the windows. Only five minutes elapsed between the time the school resource officer reported the shooting and when he found the suspect’s body, Arapahoe County Sheriff Grayson Robinson said at a press conference late yesterday. Robinson also reported that two Molotov cocktail-style bombs were found in the school. One had been set off and the other was disarmed.

Pierson, whose parents divorced in 2010, lived 4 miles from the school in Highlands Ranch and has been in the news several times over the years, all for positive reasons. He was interviewed about the design of the new quarter honoring Colorado in 2006, he submitted questions to local NBC affiliate 9NEWS about the Colorado Supreme Court in 2008, and he asked a question at a 2010 U.S. Senate debate. In addition, 9NEWS reported Pierson was on the school track team and two years ago was working on an Eagle Scout project. In searching for Pierson on Facebook, it appears a fake page has been set up, and one real Karl Pierson from California changed his profile photo to a picture of a Christmas door sign with “not the shooter” scrawled on it.

Counseling services are available today at Powell Middle School and Shepherd of the Hills Lutheran Church for students and families affected by the shooting. Arapahoe High School is closed at least through Monday.

The Associated Press contributed to this report.