Excerpts from most recent information about the gunman:
Professor Carolyn Rude, chairwoman of the university's English department, said Cho's writing was so disturbing that he had been referred to the university's counseling service.
"Sometimes, in creative writing, people reveal things and you never know if it's creative or if they're describing things, if they're imagining things or just how real it might be," Rude said. "But we're all alert to not ignore things like this."
"He was very quiet, always by himself," neighbor Abdul Shash said. Shash said Cho spent a lot of his free time playing basketball and would not respond if someone greeted him.
Classmates painted a similar picture. Some said that on the first day of a British literature class last year, the 30 or so students went around and introduced themselves. When it was Cho's turn, he didn't speak.
On the sign-in sheet where everyone else had written their names, Cho had written a question mark. "Is your name, `Question mark?'" classmate Julie Poole recalled the professor asking. The young man offered little response.
Cho spent much of that class sitting in the back of the room, wearing a hat and seldom participating. In a small department, Cho distinguished himself for being anonymous. "He didn't reach out to anyone. He never talked," Poole said.
"We just really knew him as the question mark kid," Poole said.