Someone mentioned that the original forum was offline. I had copied
and pasted his quotes into another forum. Here they were...Delete if
this is conjecture, just relaying info.

"Well, I'm screwed. They found a receipt in the gunman's pocket
indicating that he bought the gun from me in March. ATF is at my shop
right now. See you later, I'm on my way to the shop right now."

"Call BS all you like, but I just spent the last several hours with 3
ATF agents. I saw the shooter's picture. I know his name and home
address. I also know that he used a Glock 19 and a Walther P-22. The
serial number was ground off the Glock. Why would he do that and still
keep the receipt in his pocket from when he bought the gun?
ATF told me that they are going to keep this low-key and not report
this to the tv news. However, they cautioned that it will leak out
eventually, and that I should be ready to deal with CNN, FOX, etc.
My 32 camera surveillance system recorded the event 35 days ago. This
is a digital system that only keeps the video for 35 days. We got lucky.
By the way, the paperwork for Mr. Cho was perfect, thank God."

"Mr. Cho had proof of Virginia residency, checkbook (for a second ID),
and his green card(which is, of course, not green). That is all he
needed to purchase a handgun."

"We were able to burn a copy of him buying the gun."