http://www.cnn.com/CNN/Programs/anderson.cooper.360/blog/ Cho Seung-Hui bought a Glock 19 9 mm pistol 36 days ago, paying $571 for it with a credit card in an "unremarkable" purchase, the owner of Roanoke Firearms said Tuesday. John Markell, the store's owner, said Cho was very low-key when he purchased the gun and 50 rounds of ammunition. Even though Cho is a resident alien, Markell said, it was legal for him to purchase a firearm and he presented three forms of identification: a driver's license, a checkbook with an address matching the driver's license, and an insurance card. State police conducted an instant background check that probably took about a minute, the store owner said. Cho did not say why he wanted the gun, Markell said. He said the transaction -- which was with one of his associates, not Markell himself -- was "probably the most unremarkable sale ever" and he was shocked when three ATF agents arrived at his store Monday with the receipt for the weapon. The Glock 19 is one of his biggest sellers, Markell said. It's used mostly for competition and self-defense. Markell said he is shocked and saddened by the shooting at Virginia Tech.