In this case, the FBI did catch a "bad guy". They needed a warrant to do it, however, because without it they set a legal precedent that they can install a trojan on anyone's machine.
"(hmm... Firefox says that "verifiably" isn't a word, but I looked it up, turns out it's a valid adverb form of "verifiable")"
Can anyone verify this?
It's not in Merriam-Webster, so I would say Firefox is correct in this particular instance.
In any problem, if you find yourself doing an infinite amount of work, the answer may be obtained by inspection.