Convicted Minnesota businessman Tom Petters returns to federal court this week to try to shorten his 50-year prison term.

The attempt to get 20 years removed might be Petters' last chance to go after a lighter sentence for a $3.65 billion Ponzi scheme, the Star Tribune reported. The 8th U.S. Circuit Court of Appeals and the U.S. Supreme Court have already rejected his attempts to set aside his 2009 conviction and/or cut his prison term.

Petters, now 56, is to take the stand Wednesday in a courtroom in St. Paul. The main witnesses against him at the hearing will be the attorneys who defended him during his jury trial in 2009.

STORY: China's Bo Xilai, Still Defiant, Sentenced to Life in Prison

He was convicted on 20 counts of fraud, conspiracy and money laundering. He's serving his sentence in the federal prison at Leavenworth, Kansas.

At the heart of the hearing is whether federal prosecutors offered Petters a plea deal with a sentence capped at 30 years, whether Petters' attorneys relayed that offer to him, and whether he had an opportunity to accept it.

His defense team says a 30-year plea deal was discussed with Petters multiple times and that he rejected it on each occasion.