The thing about ghost guns is that anyone can print them.

Past that, they can probably get him on some kind of conspiracy to print a dearly weapon charge with the computer files. But that's a long way from putting him at the scene of the crime with the murder weapon on the day in question.

It's not even a question of if he did it. It's the problem of bringing the evidence they have in front of a jury without it getting tossed by the judge first.