Cho — who arrived in the United States as boy from South Korea in 1992 and was raised in suburban Washington, D.C., where his parents worked at a dry cleaners — left a note that was found after the bloodbath.

A law enforcement official who read Cho's note described it Tuesday as a typed, eight-page rant against rich kids and religion. The official spoke on condition of anonymity because he was not authorized to speak to the media.

"You caused me to do this," the official quoted the note as saying.

Cho indicated in his letter that the end was near and that there was a deed to be done, the official said. He also expressed disappointment in his own religion and made several references to Christianity, the official said.

The official said the letter was either found in Cho's dorm room or in his backpack. The backpack was found in the hallway of the classroom building where the shootings happened and contained several rounds of ammunition, the official said.

Col. Steve Flaherty, superintendent of the Virginia State Police, said authorities were going through a considerable number of writings.

Citing unidentified sources, the Chicago Tribune reported Cho had recently set a fire in a dorm room and had stalked some women.

Monday's rampage consisted of two attacks, more than two hours apart — first at a dormitory, where two people were killed, then inside a classroom building, where 31 people, including Cho, died. Two handguns — a 9 mm and a .22-caliber — were found in the classroom building.

The Washington Post quoted law enforcement sources as saying Cho died with the words "Ismail Ax" in red ink on one of his arms, but they were not sure what that meant.

According to court papers, police found a "bomb threat" note — directed at engineering school buildings — near the victims in the classroom building. In the past three weeks, Virginia Tech was hit with two other bomb threats. Investigators have not connected those earlier threats to Cho.

Cho graduated from Westfield High School in Chantilly, Va., in 2003. His family lived in an off-white, two-story townhouse in Centreville, Va.

"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.