WASHINGTON, April 17 (Xinhua) -- Cho Seung-Hui, a 23-year-old South Korean student who apparently killed 32 people and himself Monday morning at Virginia Tech, is described by those who know him as a "loner" and "troubled kid."

    On the first look, Cho seems to be a shy, quiet type, according to U.S. media report Tuesday.

    But many have detected there is something very wrong with him for a long time.

    Virginia Tech police on Tuesday morning identified Cho, as the killer in the worst shooting spree in American history.     

    The "question mark kid"

    A rambling note left in his dorm room reportedly railed for several pages against "rich kids" and "debauchery" and "deceitful charlatans" on campus, and at one point states, "You caused me to do this."

    A professor at the English department where Cho was studying said the student's creative-writing work was so disturbing that he had been referred to on-campus counseling services.

    In one class, he refused to speak and signed his name using a question mark. Fellow pupils called him "The Question Mark Kid."

    There were also reports that Cho had been taking medication for depression, and had also recently set fire to a dorm room and stalked women.

    Identification was delayed nearly 24 hours after the end of the rampage because Cho was carrying no ID, had no police record and had severely damaged his own face when he killed himself.

    A positive match was finally made with fingerprints on immigration records.     

¡¡¡¡"A loner"

    "He was a loner, and we're having difficulty finding information about him," Virginia Tech spokesman Larry Hincker said Tuesday morning, referring to Cho.

    Cho was born in South Korea on Jan. 18, 1984 and entered the United States in 1992 as a child of 8.

    He was a permanent resident alien, a "green card" holder entitled to most of the legal rights held by U.S. citizens.

    Cho's hometown of Centreville, Va., lies in an affluent part of Fairfax County, about 50 km west of Washington, D.C..

    His parents live in an off-white two-story townhouse on a residential street, and reportedly own a dry-cleaning business.

    Cho himself attended Fairfax County public schools, graduating from Westfield High School in Chantilly in 2003. He had a sister who attended Princeton.

    Neighbor Abdul Shash said the young man played basketball and would not respond if someone greeted him.

    He was "very quiet, always by himself," said Shash.     

    Making no friends

    Those tendencies carried on into college, where Cho apparently made it through nearly four years without making many friends.

    Classmates said that on the first day of an introduction to British literature class last year, the 30 or so English students went around and introduced themselves.

    When it was Cho's turn, he did not speak.

    Cho spent much of that class sitting in the back of the room, wearing a hat and seldom participating.

    "He didn't reach out to anyone. He never talked," one of his classmate said. "We just really knew him as the 'question mark kid.'"

    Sources told ABC News that an explanation for the mass murder may be found in the note from Cho's dorm room.

    The note apparently begins in the present tense, then over the course of several pages switches to past tense, all the while lashing out at fellow students, according to ABC and the Chicago Tribune.