A Montana cancer doctor for years saw up to 70 patients a day, double-billed federal health care programs and overprescribed pain medications to boost his income, the U.S. Attorney’s Office said Tuesday while announcing a civil lawsuit against him and a $10.8 million settlement with the hospital where he worked.

Dr. Thomas Weiner was fired from St. Peter’s Health in late 2020. He still has a medical license according to the state Board of Medical Examiners and has not been charged criminally. He maintains his innocence and has sued the hospital for firing him.

The four-year federal investigation found Weiner ordered medically unnecessary treatments, saw patients more often than necessary, falsified records to bill at higher amounts than allowed and prescribed painkillers to non-cancer patients, doing so “to increase his personal income, with little regard for the potential patient harm his conduct created,” according to the civil lawsuit filed Monday.

Federal prosecutors declined to comment on why criminal charges haven’t been pursued.