Shooter plotted in silent rage

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.