A professor who taught a student whose gun rampage at Virginia Tech left 32 people dead says she warned university officials about his behaviour.
Students are questioning whether the university failed to protect them
Lucinda Roy said she became concerned after Cho Seung-hui wrote disturbing pieces for a creative writing class.
The 23-year-old South Korean has been described as a loner and an introvert.
Virginia's governor has vowed to review authorities' handling of the shootings amid claims that the US university did not do enough to protect students.
Police said Cho killed 30 people before committing suicide. He is also believed to have killed two students earlier in the day.
Ms Roy, a former chairwoman of Virginia Tech's English Department, said that concerns arose about Cho's writings in late 2005.
Ms Roy said that she was so disturbed by what she found that she decided to take him out of the classroom for one-to-one tutoring. She also spoke to university authorities "repeatedly" about the student.
His writing "seemed very angry", she said. But the threats seemed to be under the surface and were not explicit, which was the reason why the authorities could not act, she said.
One of the reasons people were so concerned about Cho was because he barely spoke.
"He was quite a gifted student in some ways, but he seemed to be very lonely and depressed," she said.
The university has not responded to her comments.
A former classmate of Cho's, Ian MacFarlane, has also posted on the AOL news website two plays he says that Cho wrote.
In an internet blog, he described Cho's work as "like something out of a nightmare", with "really twisted, macabre violence".
The plays purporting to be by Cho are strewn with obscenities and one concludes with a man killing his 13-year-old stepson.
"When I first heard about the multiple shootings at Virginia Tech yesterday, my first thought was about my friends, and my second thought was 'I bet it was Seung Cho'," he wrote.
The university is coming under increasing scrutiny over its role in events, both before the shootings and as events unfolded.
Speaking at a news briefing on Tuesday, Virginia Governor Tim Kaine said an independent panel would carry out a "thorough" review of the authorities' handling of the disaster.
He said the panel would be appointed at the request of the university and would begin its inquiry immediately.
Gov Kaine warned against making snap judgements, saying he had "nothing but loathing" for those who took the tragedy and "make it their political hobby horse to ride".
Monday's shootings occurred in two separate locations, two hours apart.
The first took place at 0715 (1215 GMT), at West Ambler Johnston Hall dormitory, where a man and a woman were shot dead.
Then, at about 0915 (1415 GMT), 30 people were killed in the second shooting at Norris Hall, about half a mile (800 metres) away, on the same campus.
Some students have complained that they received no warning from the university until an e-mail more than two hours after the first incident.
They also said that the university should have locked down the campus immediately after the shooting at the dormitory.
But university officials defended their handling of the incidents, saying they acted on the information that they had at the time.
The New York Times, meanwhile, reports that police may have lost time pursuing the wrong man.
Citing police documents, the daily said that police went to question the boyfriend of the woman shot dead at West Ambler Johnston Hall, after being told by her roommate that he had guns at his house.
Reports of the Norris Hall shootings came in as they were questioning him, the daily said.
On Tuesday, US President George W Bush addressed a memorial service for the victims of the shootings, calling it "a day of sadness for our entire nation".