So if someone does nasty things, but getting access to evidence for these nasty things is impossible without breaking a law, how do you suggest that one should go about proving that the aforementioned nasty things were committed?
In both the case of pedophiles and state actors who are breaking the law, the answer is the same. Wait for them to slip up. It's hard to keep something secret forever.
Didn't realize the TV show "To Catch a Predator" did mass surveillance of the internet, NBC is taking investigative journalism to an extreme.
http://falkvinge.net/2012/09/07/three-reasons-child-porn-mus...
That said, in this case, were nasty things uncovered? I can't find anything about that. Also, mixing investigative journalism with theft and use of other people's credit card numbers is probably not the best way to maintain an appearance of innocence.