Seung-Hui Cho, the student who killed 32 people and then himself yesterday, left a long and "disturbing" note in his dorm room at Virginia Tech, say law enforcement sources.
He also wrote at least two violent plays for an English course that worried his professor and several classmates.
Sources described the note, which runs several pages, as beginning in the present tense and then shifting to the past. It contains rhetoric explaining Cho's actions and says, "You caused me to do this," the sources told ABC News.
Sources say Cho, 23, killed two people in a dorm room, returned to his own dorm room where he re-armed and left the note, then went to a classroom building on the other side of campus. There, he killed 30 more people in four classrooms before shooting himself in the head.
Witnesses say he was stone-faced as he opened fire. Law-enforcement sources say he may have had a romantic interest in a young woman who was found dead after the first shootings.
Lucinda Roy, a co-director of the creative writing program at Virginia Tech, taught Cho in a poetry class in fall of 2005 and later worked with him one-on-one after she became concerned about his behavior and themes in his writings.
Roy spoke outside her home Tuesday afternoon, saying that there was nothing explicit in Cho's writings, but that threats were there under the surface.
Roy told ABC News that Cho seemed "extraordinarily lonely--the loneliest person I have ever met in my life." She said he wore sunglasses indoors, with a cap pulled low over his eyes. He whispered, took 20 seconds to answer questions, and took cellphone pictures of her in class. Roy said she was concerned for her safety when she met with him.
She said she notified authorities about Cho, but said she was told that there would be too many legal hurdles to intervene. She said she asked him to go to counseling, but he never did.
One play attributed to him, called "Richard McBeef," describes a 13-year-old boy who accuses his stepfather of pedophilia, and ends with the boy's death.
In another, called "Mr. Brownstone," three high-school students face an abusive teacher.
"I wanna kill him," says one character.
"I wanna watch him bleed like the way he made us kids bleed," says another.
The two plays were posted on AOL after a staffer named Ian MacFarlane, a December 2006 graduate of Virginia Tech, brought them to his editors' attention.
MacFarlane said he was in a class with Cho in which students were required to post their plays online for peer review and comment.
AOL editors verified the authenticity of Cho's works before posting them, according to Alysia Lew of AOL Corporate Communications.
At a late-afternoon news conference, police said they had searched Cho's dorm room. "There were considerable writings that were reviewed," said Col. Steven Flaherty, Superintendent of the Virginia State Police.
A 'Troubled' Young Man
Some news accounts have suggested that Cho had a history of antidepressant use, but senior federal officials tell ABC News that they can find no record of him in the governments files on controlled substances. This does not completely rule out prescription drug use, including samples from a physician, drugs obtained through illegal Internet sources, or a gap in computer databases, but the sources say theirs is a reasonably complete search.
(NOTE: Some readers may have inferred from an earlier edition of this story that the federal government keeps a comprehensive record of all prescriptions. The Drug Enforcement Agency says it does track prescriptions of so-called controlled substances -- including some mood-altering medications -- but not all prescriptions made in the United States.)
Cho, born in South Korea, was a legal resident alien of the United States. He was a senior at Virginia Tech, majoring in English.
Sources tell ABC News Cho bought his first gun, a Glock 9 millimeter handgun, on March 13; they say he bought his second, a Walther .22 caliber pistol, within the last week. The serial numbers on both guns had been filed off, they said.
Authorities found the receipt for the 9 millimeter handgun in Cho's backpack. They say the bag also contained two knives and additional ammunition for the two guns.
Legal permanent resident aliens may purchase firearms in the state of Virginia. A resident alien must, however, provide additional identification to prove he or she is a resident of the state.
Sections of chain similar to those used to lock the main doors at Norris Hall, the site of the second shooting that left 31 dead, were also found inside a Virginia Tech dormitory, sources confirmed to ABC News.
President Bush and the first lady addressed the Virginia Tech community at a convocation Tuesday afternoon.
"Yesterday began like any other day. Students woke up and they grabbed their backpacks and they headed for class," Bush said. "And soon the day took a dark turn, with students and faculty barricading themselves in classrooms and dormitories."
"For many of you here today, it was the worst day in your lives," Bush said.
Positive Fingerprint Match
Cho's identity has been confirmed by matching fingerprints on his guns with his immigration records.
"Lab results confirm that one of the two weapons seized in Norris Hall was used in both shootings," Virginia Tech Police Chief Wendell Flinchum said at a press conference Tuesday morning.
Cho, according to law enforcement officials, had entered the country through Detroit with his family in 1992, at the age of eight. He last renewed his green card in 2003. As of yesterday, his home address was listed as Centreville, Va., and the university reported he was living in a campus dormitory, Harper Hall.
Cho's parents live in a townhouse development in Centreville, a suburb of Washington. They own a dry-cleaning shop nearby.
His older sister, Sun-Kyung, graduated from Princeton University in 2004. A source, who asked to be identified as a senior Administration official, said she works for McNeil Technologies, a firm contracted by the State Department to manage reconstruction efforts in Iraq.
Police searched the family home last night. On Tuesday, no one was answering their door.
One neighbor, Marshall Main, describes Cho's parents as quiet and polite. Neither Main nor another neighbor recalled seeing the son in recent years.
Cho graduated from Westfield High School, a Fairfax County public school, in 2003. The school system says two of the dead yesterday at Virginia Tech had graduated from Westfield in 2006; they would have been freshmen when Cho was a senior.
Two-Hour Gap Between Shootings
Police say Cho killed two people in West Ambler Johnston Hall, a dormitory near his own, shortly after 7:00 a.m. Monday. Then, two hours later, he opened fire in Norris Hall, a classroom building across campus.
Reporters continued to ask today why administrators did not cancel classes after the first shooting, and why it took more than two hours to inform the university community via e-mail about the first incident. The first e-mail notifying students of the dorm shooting was not sent by the school until 9:24 a.m -- by which time the second shooting was already over.
According to President Charles Steger, the administration locked down West Ambler Johnston Hall dormitory after the first shooting. But he said classes weren't canceled because the shooting was believed to be tied to a domestic dispute and campus police believed the shooter had left the campus.
"The second shooting, no one predicted that was also going to happen that morning," Steger said. "So if you're talking about locking it down, what is it you're going to lock down? It's like closing a city. It doesn't happen simultaneously."
By Monday night, investigators had ruled out the possibility of a murder-suicide in the first dormitory shooting. Ryan "Stack" Clark, a member of the school's marching band, the Marching Virginians, and a student resident assistant, was killed there by a shot in the neck. His next-door neighbor, freshman Emily Hilscher, was also found dead.
At Norris Hall, the gunman left a trail of bloodshed, which Flinchum, the Virginia Tech police chief, called "one of the worst things I've seen in my life."
Cho apparently shot himself in the head after the killings; part of his face was missing when his body was found.
Questions About Earlier Bomb Threats
Police documents today showed authorities suspected Cho may have been the source of two bomb threats last week targeting Virginia Tech engineering buildings.
The first of the two threats was directed at Torgersen Hall, a classroom and laboratory building, while the second was directed at multiple engineering buildings. Students and staff were evacuated, and the university sent out e-mails across campus, offering a $5,000 reward for information about the threats.
Virginia Tech -- formally known as Virginia Polytechnic Institute and State University -- is located in the western end of the state near the borders of West Virginia and Tennessee. It has more than 25,000 full-time students. Its campus, which spreads over 2,600 acres, has more than 100 buildings.
The number of dead is almost twice as high as the previous record for a mass shooting on an American college campus. That took place at the University of Texas at Austin on Aug. 1, 1966, when a gunman named Charles Whitman opened fire from the 28th floor of a campus tower. Whitman killed 16 and injured 31.
ABC News' Amy Thomas and Jason Ryan contributed to this report.