FDR was an evil SOB.
Yup. Note that the part about forcing Mellon to disclose all of his wealth was solely for one reason: it was the depression an fat cats were not looked on kindly by struggling people. FDR was explicity trying to bias the public and the jury pool against Mellon simply by making him say just how rich he was out loud, in public. Since there was no crime, he clearly was looking to send him to jail for (1) not paying the worst case taxes he could have paid if he hadn’t used legal avoidance strategies and (2) being super rich and (3) criticizing FDR (the real one)