How do the police even stumble on the fact that this guy was involved? Did they take down a pedophilia source and then rip through the web server logs? (That s

How do the police even stumble on the fact that this guy was involved? Did they take down a pedophilia source and then rip through the web server logs? (That seems legit.) Or were they monitoring IP traffic on a larger scale, knew of a pedophilia source, let it continue running and simply harvested IP addresses that were connecting with it? (Sounds like a privacy issue.) Regardless -- how does a good guy help without putting himself in legal hot water?