Chris Davids, a Virginia Tech senior who graduated from Westfield High School in Chantilly, with Cho in 2003, recalled that Cho almost never opened his mouth and would ignore attempts to strike up a conversation.
Once, in English class, the teacher had the students read aloud, and when it was Cho's turn, he just looked down in silence, Davids recalled. Finally, after the teacher threatened him with an F for participation, Cho started to read in a strange, deep voice that sounded "like he had something in his mouth," Davids said.
"As soon as he started reading, the whole class started laughing and pointing and saying, 'Go back to China,'" Davids said.
Cho was born in South Korea.
The high school classmates' accounts add to the psychological portrait that is beginning to take shape, and could shed light on Cho's state of mind in the video rant he mailed to NBC in the middle of his rampage Monday at Virginia Tech. He shot 32 people to death and committed suicide in the deadliest one-man shooting rampage in modern U.S. history.
"What he has shown in this video is he's a psychopath," criminal profiler Pat Brown told CBS' The Early Show. "He wasn't crazy, because he knew exactly what he was doing," Brown said.
However, police said Cho's video and writings revealed no new information for their investigation.
"The package simply confirmed what we already knew," Col. Steve Flaherty, Virginia State Police superintendent, said Wednesday.
Investigators have criticized the media for broadcasting images that they say glorified Cho and inflicted new pain on those already shattered by his rampage, reports CBS News correspondent Bob Orr.
"We are disappointed in the editorial decision to broadcast these disturbing images," said Steve Flaherty of the Virginia State Police.
Many on Virginia Tech's campus agree, Orr reports, saying they've now been victimized twice.
"He put that video out there so everyone could see it, which means we're doing his wishes which I don't agree with at all," junior Mark Twigger said.
In the often-incoherent video, the 23-year-old Cho portrays himself as persecuted and rants about rich kids.
"Your Mercedes wasn't enough, you brats," says Cho, who came to the U.S. in 1992 and whose parents work at a dry cleaners in suburban Washington. "Your golden necklaces weren't enough, you snobs. Your trust funds wasn't enough. Your vodka and cognac wasn't enough. All your debaucheries weren't enough. Those weren't enough to fulfill your hedonistic needs. You had everything."
Click hereto watch Cho Seung-Hui's chilling video.
Among the victims of the massacre were two other Westfield High graduates: Reema Samaha and Erin Peterson. Both young women graduated from the high school last year. Police said it is not clear whether Cho singled them out.
Stephanie Roberts, 22, a fellow member of Cho's graduating class at Westfield High, said she never witnessed anyone picking on Cho in high school.
"I just remember he was a shy kid who didn't really want to talk to anybody," she said. "I guess a lot of people felt like maybe there was a language barrier."
But she said friends of hers who went to middle school with Cho told her they recalled him getting picked on there.
"There were just some people who were really mean to him and they would push him down and laugh at him," Roberts said Wednesday. "He didn't speak English really well, and they would really make fun of him."
Virginia Tech student Alison Heck said a suitemate of hers on campus — Christina Lilick — found a mysterious question mark scrawled on the dry erase board on her door. Lilick went to the same high school as Cho, according to Lilick's Facebook page. Cho once scrawled a question mark on the sign-in sheet on the first day of a literature class, and other students came to know him as "the question mark kid."
"I don't know if she knew that it was him for sure," Heck said. "I do remember that that fall that she was being stalked and she had mentioned the question mark. And there was a question mark on her door."
Heck added: "She just let us know about it just in case there was a strange person walking around our suite."
Lilick could not immediately be located for comment, via e-mail or telephone.
On Wednesday, NBC received a package containing a rambling and often incoherent 23-page written statement from Cho, 28 video clips and 43 photos — many of them showing Cho brandishing handguns. A Postal Service time stamp reads 9:01 a.m. — between the two attacks on campus.