Lets just give thanks that he, like so many other criminals, are complete idiots and post to the internet their guilt, for all the world to see.
A sobering thought is how many are not caught because of self incrimination.
my guess is he traded his molestation pictures on line through E- mail or aq direct messaging service with some one who ended up posting them on line. from there facial recognition software found a match to the name of one of the per network users and more child porn was found. a lot of times theses idiots don’t understand that when they trade it on line the person they trade with might post it some where that is more open to law enforcement finding it.