The closest thing to prison for Rossi I could find was this quote:
““Pay close attention to Andrea Rossi; he has a dirty past. Twenty years ago he was arrested for illegal importing of gold from the Swiss.”
Doesn’t say he went to prison; and I’m not sure how bad a crime it is to “illegally import” gold.
There was suggestions of a scam involving waste disposal, but no arrest record I could find.
It is there somewhere, maybe it was jail.
He was in there for 3 year sentence and got out after 1.