I think Satoshi is the NSA. This is 99% because it would be the most entertaining result, and 1% actual reasoning ( https://news.ycombinator.com/item?id=6206086 ).
If it's part of a policing effort, then it's obviously part of the UN, which according to Tim LeHaye, rules over the United States with an iron fist and is where the shadow government of totally-not-Jews would do exactly this kind of thing.
The only name I have for that is New World Order.
If Bitcoin is a targeted strike against China somehow (not completely impossible), then the CIA is the likeliest candidate. Otherwise, of the USGov national agencies, the NSA is most likely.
The FBI doesn't really get anything out of it. The only reason I can think of for the FBI to do it is for paying off informants anonymously. (And as I've pointed out before, if anyone's an expert on money laundering, it's the FBI.)