OP you aren’t still worried that there is even a minuscule chance that he is telling the truth are you?
You can log the 101 ways this is situation is ‘off’ as per the feedback in the thread but really all you are left with now is waiting for his next move.
It might all blow over - I wonder if he senses he’s been rumbled he will play into the he’s been scammed situation or let it all fade away.
He sounds deluded enough to do that.
Have you alerted your elderly relatives that he might ask for money - or maybe the situation might be that he has already borrowed money and is looking for a way not to pay it back?
Would he actually clear off on a once in a lifetime holiday?
Or has he possibly debts and/or addictions to finance?
Looks like your next steps are:
Asking him about things as he has opened up communication.
Keeping in touch with elderly relative re the situation - especially about money.
Consider seeking (anonymous in the first instance?) elder financial abuse advice from SS / Age U.K.?
Consider speaking to his parole officer?
I don’t think that there is much merit in a wild goose chase trying to prove him wrong with PALs etc. - this will all inevitably come out in the wash on its own - not sure you need to entangle yourself in that part as it could back fire.