Of seven students taking music theory at Westfield High School in Chantilly, Va., in 2001-02, six were "pretty cozy and friendly with one another," recalls one of them, Greg Moore. The seventh, Cho Seung-hui, "was sort of there in the corner, just getting by," Mr. Moore says. "In that entire year, I don't think I ever heard him say as much as a single word."
The first time Mr. Moore says he heard Mr. Cho speak was on TV in April -- on a videotape the Korean immigrant mailed the same day he murdered 32 students and faculty members before killing himself at Virginia Tech.
Mr. Cho didn't need to talk to succeed academically at Westfield. Diagnosed with "selective mutism," or anxiety-related refusal to speak, he was placed in special education under the "emotional disturbance" classification. As a result, he was largely excused from making oral presentations and answering teachers' questions in class; oral participation was de-emphasized in his grading. Aided by such "accommodations," or efforts to compensate for his disability, he achieved A's and B's in regular and Advanced Placement courses and was admitted to Virginia Tech.