Probably the FBI for the public part of it, but if this wasn't a US owned operation you can be sure the CIA/NSA/military will do their own investigation.
> It's not actually unusual for three-letter US agencies to be at odds with one another.
I'd noticed that; this seems to have been the case for a long time. You'd think that having state security agencies at war with one-another would be a disaster, but perhaps it's a feature: a sort of social "layered security". At any rate, it seems much better than having a bunch of state security agencies that all sing from the same songsheet.
It's a bog standard practice, actually, even if you look very far back to the ancient world. Having a single agency responsible for security of yourself and what you own is a bad idea because no matter how much you try ensure the loyalty of people in it, it's prone to, at the minimum, suppressing its own failures and magnifying its successes to make itself look better than it actually is, giving you a false sense of security. It is also the natural point from which to orchestrate a coup, which is something that can be used by your adversaries, but even without their involvement people working there eventually realize that they hold all the keys to the kingdom and there's little risk in them just taking over.
So rulers in all ages tended to create multiple different security apparatuses for themselves and their states, and often actively encouraged rivalries between them, even if that makes them less efficient.
