CHICAGO (AP) — A federal judge has sentenced a Chicago-area chiropractor to 6 ½ years in prison for defrauding a private health insurance company.

U.S. District Judge Ronald Guzman sentenced 51-year-old Bradley Mattson of Lake Forest on Monday and ordered him to begin serving his sentence on Jan. 25. Mattson also must pay almost $2.1 million in restitution.

Mattson pleaded guilty in September to defrauding Blue Cross and Blue Shield of Illinois.

He admitted that between 1999 and 2009, six suburban clinics he owned with two co-defendants submitted nearly $5.9 million in false claims for services that were not medically necessary or were never provided to patients. The clinics collected almost $2.1 million.

Co-defendant Steven Paul of Northbrook also pleaded guilty and awaits sentencing. Charges are pending against co-defendant Neelesh Patel of Northbrook.