I echo the responses so far – that absolutely sucks. I can only imagine what you are going though. I’d be absolutely gutted if that happened to somebody in my life. But it sounds like you did what you could, so try not to feel guilty about it!
In my minimally-informed opinion, I’d say it’s unlikely your dad will see any of his money again as a result of any investigation into his specific case. The only chance is probably (again, imo) from a larger investigation that results in one of the big scammer groups getting busted.
With that in mind, I would make sure that whatever evidence is available is in the hands of one or more law enforcement agencies, in particular somebody at the federal level. Things like the phone number(s) they used (which should be connectable to somebody), the QR code that facilitated the Bitcoin transaction (that must have gone to some URL at a domain that was registered to somebody), etc.
Unfortunately, I think it’s likely only the feds would have enough know-how and the power to follow those threads where they lead, and $30k is likely not enough to have them go after your dad’s case specifically. But maybe if there is a larger effort that nabs someone down the road, and your dad’s case could be linked to them, they could recover some money for him? (Sweet Summer Child mode…)
A couple other random thoughts:
Maybe AARP has resources on next steps for people in this situation? As well as “prevention” resources (both for you and for the rest of us on the forum who now have this on our list to talk to our parents about).
Maybe the state AG where he lives could help? At a minimum they might know which law enforcement agency would be most likely to be helpful.
Finally, it’s crazy that this kind of thing is so commonplace that it’s the setup for a movie like The Beekeeper. You might not want to watch it right away due to triggers – on the other hand you might enjoy the payback – but it’s remarkable how many aspects of your dad’s story are right in line with how the scam unfolds in the movie.
Anyway, best of luck! If there’s a silver lining, it’s that many of us here will be checking in with our people, and maybe we can keep them from getting scammed.