If I get a huge sum of money & can't show where it came from am I in legal trouble?

I think you’re right.

The moral to this whole story is one should never make an enemy of a rich ventriloquist after you give him keys to your basement.

The burden of proof is still on the authorities.
They won’t find a shred of evidence of anything, so they can’t link you.

So declare it for tax, and what are they going to do? Investigate you to death? (Which has happened I suppose :stuck_out_tongue: ).