From this article posted...
Of all 56 prosecutions, the ones which led to imprisonment ended with acquittals; only 5 of the prosecutions for tax crime ended with convictions (with some custody imprisonments). All of the other prosecutions ended with acquittal or for statute of limitation. The same Petroldragon and Omar customers, even those who suffered factory seizures or prosecutions because of involvement with Rossi’s companies, testified as witnesses in favor of the defendant .
That's Rossi's side of the story. He has "character issues." Do you have any other source?