"No one has pled guilty, but plea discussions are ongoing," an anonymous source told columnist Michael Sneed.
In October, the Sun-Times reported on the existence of the federal probe, being run out of the FBI's Washington D.C. field office. According to the paper, Jackson was being investigated for allegedly using campaign funds to decorate his home.
The probe apparently began before June 10, when Jackson collapsed in his Washington D.C. home. The lawmaker has been on medical leave since, and spent the summer being treated for bipolar disorder in Minnesota and Arizona.
Jackson was recently spotted in Washington D.C. by a reporter for The Daily, but according to the Sun-Times he is now back receiving treatment at the Mayo Clinic in Rochester, Minn.