One law enforcement official said Cho's backpack contained a receipt for a March purchase of a Glock 9 mm pistol. Cho held a green card, meaning he was a legal, permanent resident, federal officials said. That meant he was eligible to buy a handgun unless he had been convicted of a felony.

Roanoke Firearms owner John Markell said his shop sold the Glock and a box of practice ammo to Cho 36 days ago for $571.

''He was a nice, clean-cut college kid. We won't sell a gun if we have any idea at all that a purchase is suspicious,'' Markell said. Markell said it is not unusual for college kids to make purchases at his shop as long as they are old enough.

http://www.nytimes.com/aponline/us/A...l?pagewanted=2