I would say the first phone call should be to a good lawyer anytime the Feds are involved.
Nephew was fishing in CT a few years ago and a large black bear approached him; he shot and killed it with his (legal) handgun, reported it immediately, and was arrested for killing the bear. Cost a lot of legal fees but he did get off - prosecution said the bear wasn’t close enough to count as a threat (defined as 15 yards), defense said if it was close enough to be killed with one handgun round it was close enough to be a threat.