A student who walked into his suburban Denver high school with a shotgun looking for a specific teacher was a skilled debater with strong political views who recently was kicked off the speech and debate team, according to students and a teacher.

Karl Pierson, 18, critically wounded a student before apparently killing himself Friday at Arapahoe High School as police moved in. His body was found about a half-hour after the shooting was reported.

Steve Miles, an English teacher who taught Pierson as a freshman, said Saturday that the school librarian who ran the speech team cut Pierson from the team, but he didn't know why.

"I think he (Pierson) really cultivated his speech and argument skills and really thought that was a big part of his identity. ... He probably thought it was a pretty crushing blow to get kicked off the debate team," Miles said.

It's unclear whether the librarian was the person Pierson was searching for when he entered the school with a gun. Authorities haven't identified Pierson's target, but students say the librarian was the one he was seeking. Sheriff Grayson Robinson has described the target as a teacher.

Senior Dillon Johnson, 17, said he thinks that when Pierson lost his platform to share his passionate views through the debate team, it "set him off."

Students described Pierson as an outspoken, sometimes goofy and smart student who often would talk about his beliefs during class, sometimes even debating his teachers. They also said he was an Eagle Scout who finished at the top of speech competitions.