Police pored over the writings of a student who massacred 32 people at Virginia Tech university as they searched yesterday for further clues to why he went on the worst shooting rampage in modern US history.

A chilling portrait of Cho has emerged from accounts of fellow students and teachers and from writings for his English degree that were dominated by disillusioned, violent characters.

"I felt he was a very lonely, isolated kind of person the whole time," Lucinda Roy, an English professor who taught Cho, told CNN on Tuesday. "He would always wear sunglasses even inside, and a cap."

As students and teachers grieved, police said they were examining Cho's "considerable" writings for clues about what may have sparked Monday's rampage on the rural campus.

Above: Students take part in a candlelight vigil a day after the killings at Virginia Tech on Tuesday. Inset: A Virginia Tech cadet plays taps during a vigil on the campus on Tuesday. [Reuters]

The Washington Post and other media quoted police sources as saying Cho left a note attacking what he called rich, spoiled students. Police said there was no suicide note.

He was found with the words "Ismael Ax" written in red ink on one of his arms, the Post reported law enforcement sources as saying. It was unclear what the words meant.

Probe into response

With many students still angry about the university's failure to shut down the campus after the first shooting, Virginia Governor Tim Kaine was working to appoint a team of independent officials to examine the response.

Neighbors, roommates and teachers described Cho as a withdrawn person who rarely talked to anyone. Two students who said they were Cho's roommates said he had harassed several female students and once told them he wanted to kill himself, which prompted the roommates to report concerns about him to the police.

The massacre has revived the debate over US gun control laws, which are the most lenient in the Western world. But it appeared unlikely the shooting would lead to stricter laws or have much impact on the 2008 presidential race because most leading candidates already favor gun controls and are unlikely to gain by pushing the issue.

President George W. Bush, in an interview on NBC on Tuesday, refused to answer questions on the gun control issue.

"Now is not the time," he said. "I'm more interested in helping people heal right now. And that's why we're here."

The university, which has 25,000 full-time students, held a memorial service and candle-lit vigil on Tuesday as students struggled with shock and grief. Piles of stuffed animals, flowers and slips of papers with scrawled memories and messages to the victims were growing up around the campus.

"Rest in peace fellow Hokies," said one handwritten note, a reference to the nickname of the school's athletic teams. "I will never forget you."