I think this guy is gonna walk. If he has any sort of attorney, they will get all of the evidence relating to how the firearm is tied to the shooter made inadmissable. The Fed's screwed up when they used the 4473's and the no longer secret registration database in violation of federal law, via the Brady act, to tie the shooter to the gun. If they can't admit the firearm tie-in, they don't have a case. Reality says that he will be convicted in the lower court, and have it overturned on appeal.
What are "4473's" and what is the registration database (and how is it no longer secret?) you are talking about?
These are the yellow forms that citizens are required to fill out at the purchase counter in order to conduct a background check and facilitate the purchase of a firearm anywhere in the United States. They are kept in perpetuity by the dealer who has a Federal Firearms License (FFL). If and when an FFL goes out of business, he is required to turn all of these forms over to the ATF.
The ATF may inspect these forms at the dealers place of business without a warrant, but may not copy, or otherwise collect the information on these forms for the purpose of creating a "registration" or "database" of gun owners. So says the "law".
The reality is quite different.