While I know nothing about the case besides what's on that site I linked, my best guess is that he was part of one of those pedo online networks where they all exchange child porn with one another. Those networks are hard to crack because they're careful who they let in, and often the initiation involves sharing a video they hadn't seen before, which puts law enforcement in an awkward position because they don't want to distribute child porn themselves.

Sometimes law enforcement cracks one of these networks by busting a pedo on an unrelated matter, seizing his computer, and then taking over his account.

Once law enforcement is into one of these networks, they wait for the pedos to exchange videos/pics to incriminate themselves, and then they get a warrant from the various ISPs involved and identify the people behind the screen names.

My guess is that 4Dragons was on one of these networks, and got caught up in one of those.

It does not seem from the charges that he produced any child porn, nor does it seems he's accused of actually molesting any children.

Still disturbing stuff, though.

It's also worth noting that "child porn" is any pornography featuring kids under 18. It does not specify which kind of child porn he was caught downloading/distributing -- whether it was teenagers, or whether it was little kids. Hopefully it was the former. Bad either way, but those who get sexually turned on by young kids are on a whole different level of sick.