LITTLETON, Colo. -

Documents show that a teen who fatally shot another student at a Colorado school last year had been deemed "not a high-level of threat" after shouting a death threat against his debate coach three months earlier.
    
Authorities have said 18-year-old Karl Pierson was targeting the coach when he entered Arapahoe High School in December armed with a shotgun, a machete and homemade bombs.
    
Pierson killed a 17-year-old girl before taking his own life in the school library. The debate coach - a librarian - escaped unharmed.
    
The disciplinary records obtained by The Associated Press also show that Pierson was sent home from school early two days before the shooting after he pounded on a locked classroom door so hard that teachers in other classrooms could hear it.