My supposition would be these are related to search warrants served offsite perhaps at his home or the home of associates or family. The criminal charges may be related to the child porn found on his computer. An investigation like this probably turns over quite a few rocks.
I doubt though that the DA plans to pursue the firearm suppliers unless they are trying to use what happened as a means to initiate RICO against them. A tactic which has been suggested by gun control zealots in the past.