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.
