The allegation (which I believe based on personal knowledge) was that Rubashkin or people acting in his behalf were selling US worker visas in foreign countries.
Once the visa-holder arrived, they didn’t work for the meat plant but moved elsewhere. The meat plant then hired illegals in their place.
Probably the fraud conviction instead was to help cover a widespread illegal practice that big business political donors like.
Then the prosecutors should have charged him with that. Then he could be imprisoned for that, if convicted. The fraud conviction had nothing to do with immigration, rather money laundering, transferring funds from an account serving as collateral for a bank loan to another account, falsely identifying them as accounts receivable. He claimed no knowledge of the companies involvement employing illegals. I’ve not a clue if he’s telling the truth, but the state jury on immigration charges did and acquitted him. I believe several lower level employees were convicted on immigration charges.