The 23-year-old student who went on a bloody rampage at Virginia Tech had prepared the attack for weeks -- buying two semiautomatic pistols and writing a dark, hate-filled rant in his dormitory room before setting out with a backpack of ammunition to kill students and teachers, authorities said Tuesday.
Seung-hui Cho, a child immigrant from South Korea who grew up in the Washington suburbs, was portrayed by fellow students and teachers as an insecure loner who ate by himself night after night, watched TV wrestling shows alone and, when spoken to, had little to say.
Well-known poet Nikki Giovanni, who taught him creative writing, observed him in the class with dark sunglasses and a ball cap jammed down over his face. He turned in assignments she found disturbing. Sometimes he snapped unwanted cellphone photos of classmates. Students stopped showing up for class, telling her, "The guy's really creepy." At one point she had guards stationed nearby.
Authorities continued Tuesday to assemble the pieces of Cho's life on the campus of 26,000 students near the Blue Ridge Mountains, but his motivation was still unclear. No link has been disclosed between Cho and any of the victims, and police continue to look for evidence that he first shot two students in a dorm before the bloodier attack 2 1/2 hours later, when he killed 30 more and himself, and injured more than two dozen.
"We're still following all these leads. There's a myriad of leads," said state Police Superintendent Col. Steven Flaherty. "There is a lot of evidence, and it's slow-moving."
Cho apparently had no friends or a girlfriend, said Joseph Aust, one of his five roommates. He wore a standard uniform -- blue jeans, T-shirt and maroon Virginia Tech hat, and kept only textbooks and a laptop computer. His one known passion was downloading music.
He hung no pictures, posters or decorations on his walls, and avoided conversations with his roommates and other students.
"He would just give one-word answers," Aust said.
But in recent weeks Cho's habits changed. He ventured out at night to the campus gym, lifting weights to beef up his skinny frame. He trimmed his hair into a military-style buzz cut.
Cho, a senior majoring in English, was normally in bed by 9 each night, up again by 7 in the morning. But he began rising earlier, sometimes by 5:30 a.m., to put in his contact lenses, take prescription pills and apply acne medicine.
Police said they had found "considerable writings" in his dorm room, including rants about wealthy kids and debauchery.
Despite Cho's inner turmoil, he carried out his last acts with calm determination.
He sent bomb threats to school officials, authorities believe. He chained the doors on Norris Hall and brought along enough ammunition to kill 50. Police also said he tried to shave the serial numbers off his new Walther P22 and 9-millimeter Glock, both heavy handguns. And he carried no identification.
In his final moments, shooting point-blank at students and professors, firing through doors at others who tried to barricade themselves from him, he seemed never to lose his nerve, often reloading.
He hit many people three or more times at close range.
"I'm sure the behavioral people will be looking into what it was that set this kid off," said a federal law enforcement official familiar with the investigation.
The first attack occurred at 7:15 a.m., when Emily Hilscher, a student, and Ryan Clark, a resident advisor, were shot to death at the West Ambler Johnston dorm.
Hilscher's roommate, Heather Haugh, said her friend did not know Cho and she knew no reason he would first turn his violence upon her.
"I've never seen him," she said. "I don't know his name. Emily didn't know him, as far as I know."
She said that speculation about a domestic dispute probably stemmed from the fact that she told police that Hilscher's boyfriend, Karl David Thornhill, was an avid gun user.
After the second shooting at 9:40 a.m. at Norris Hall, Haugh said she was summoned again by police who knew only that the killer was Asian.
"They didn't know who he was and they just asked me if [Hilscher] had any fights with Asian people," she said. "And I said no and that I don't know anyone who would want to hurt her."
She said the dorm room she shared with Hilscher was behind the elevator bank in the residence hall, an unlikely place for a random shooting.
A law enforcement source said Cho bought one of the guns, the .22-caliber Walther, at JND Pawnbrokers in Blacksburg in February, and the other, a Glock Model 19 that retails for more than $500, on March 12 at the Roanoke Firearms store in Roanoke, Va.
Both were bought legally, said the federal official, and both licensees did everything required, including background checks.
At a Tuesday morning news conference, campus and state police announced that ballistics tests showed that one of the two handguns fired by Cho in Norris Hall was also used to kill the two students in the dorm.
Even so, Flaherty, the head of the state police, said they could not conclusively prove that Cho shot people at both locations. "The evidence has not led us to where we can say with all certainty that the same shooter was involved in both instances," he cautioned.
He stressed the same point at a second news conference eight hours later. "We've not been able to make that evidentiary leap at this point to say that Cho is the individual who did those shootings," he announced.
That raised the possibility of an accomplice, a notion Flaherty did not entirely dismiss. Though he said it was "reasonable to assume" that Cho acted alone in both locations, he added: : "We are exploring whether or not there was someone who may or may not have helped Cho at any point during his planning or during his execution."
After the dorm shootings, and before Cho burst into Norris Hall, police were focused on Thornhill, their initial "person of interest." They said Thornhill was stopped in his car off campus and questioned.
The affidavit suggested that police did not believe Thornhill's account of where he had stored his guns -- at his home in Blacksburg or at his parents' home in Boston, Va. Police searched a home in Blacksburg on Tuesday morning, looking for "firearms, ammunition, bloody clothing, footwear and other tangible evidence associated with the alleged murders."
It is not known what they found, if anything.
Thornhill has not been arrested, according to police. But Flaherty, without naming Thornhill, said he "remains a person of interest and probably will be looked to for evidentiary information."
Thornhill could not be reached for comment. A man who answered the door at the Blacksburg home Tuesday afternoon said no one named Thornhill lived there.
It also was unclear whether Thornhill knew Cho, who shared a three-bedroom suite in Harper Hall with five roommates, some of whom barely knew how to pronounce his name.
Born Jan. 18, 1984, Cho immigrated to the United States from South Korea in September 1992, arriving first in Detroit, according to the Korean Embassy in Washington. He renewed his green card status in October 2003 but apparently retained his South Korean citizenship.
His parents moved to Centreville, Va., about 20 miles west of the capital, and reportedly ran a dry cleaning business in the fast-growing suburb that has drawn many South Korean immigrants.
Cho attended Westfield High School and was a member of the science club, school officials said. He graduated in 2003.
Virginia state police teams searched the family home for evidence late Monday night. The family lived in an off-white, two-story town house in a cul-de-sac of middle-class homes. The home was deserted Tuesday.
Cho's first name, in capital letters, was still posted Tuesday on an orange tag taped next to the door to his dorm room, No. 2121. The living room featured a burgundy sofa, a small coffee table and an array of empty water bottles and soda cans.
His roommates said they had not noticed any weapons or unusual items -- except Monday morning, after Cho left for class, when Aust saw a screwdriver on his roommate's desk.
Other times, Aust found Cho sitting silently in a desk chair, apparently oblivious. "He'd just kind of be staring at his desk, just staring at nothing," he said. "I would pass it off like he was just weird."
Several students and professors who had seen Cho's poetry, plays and fiction from 2005 described it as filled with graphic violence.
Lucinda Roy, chairwoman of the English department, worried about his stability and urged him to seek counseling at the school. He apparently did not.
Giovanni, the former creative writing instructor, said she took some of Cho's writing to Roy and told her that she could no longer teach him.
"I couldn't allow him to destroy my class," she said.
Roy agreed to teach Cho in a private tutorial setting, Giovanni said.
Roy gave Cho an A for the semester. Giovanni thinks he got the grade not for talent or effort, but because he was "intimidating" -- and that it was decided it was best to keep him happy.
"I think he liked the idea that he was a scary guy," Giovanni said. "Some people like that. That's how they define themselves."
Stephanie Derry, a senior English major, took a playwriting class with Cho this spring, according to the campus newspaper, Collegiate Times. Cho barely spoke to the other students, she said.
"His writing, the plays, were really morbid and grotesque," Derry told the paper. "His kind of writing was pretty peculiar, but when we asked him if he had any comments after we'd reviewed his work, he would just shrug and say nothing."
Two of Cho's plays, which Derry vividly recalled, have been posted online. In one, three students trade vicious, scatological banter about killing their teacher. In the other, a boy accuses his stepfather, Richard McBeef, of killing his father. "I hate him," he says. "Must kill Dick. Must kill Dick. Dick must die." The play ends wordlessly, with stage directions: "(Out of sheer desecrated hurt and anger, Richard lifts his large arms and swings a deadly blow at the thirteen year old boy.)"
Another student in the dorm suite, Karan Grewal, 21, also said he found Cho a mysterious figure. He said Cho would type on his laptop and rarely acknowledge the others in their shared living room.
Grewal said he greeted Cho twice but got no response; he stopped trying to be friendly. "He really just sat there and didn't say anything," he said. "We all talked to each other, except for him."
Grewal stayed up all night Sunday to study and was in the suite's shared bathroom at about 5:30 a.m. Monday when he noticed Cho was already up and dressing. He was wearing boxer shorts and a T-shirt.
"He was, like, normal," Grewal said.
Serrano and Drogin reported from Washington, Zucchino from Blacksburg. Staff writers Richard Fausset, Erika Hayasaki, Josh Meyer, Greg Miller and Richard B. Schmitt contributed to this report.