SIOUX FALLS, S.D. (AP) — Federal prosecutors say a South Dakota neurosurgeon made millions of dollars by performing unnecessary and dangerous surgeries, including one that left a patient partially paralyzed.

The Department of Justice alleges in a lawsuit filed Wednesday that Dr. Wilson Asfora enriched himself by using medical devices he invented during surgeries and receiving kickbacks from companies whose devices he used without disclosing the arrangements.

The Argus Leader reports that Asfora performed complex spinal surgeries that shouldn’t have been done and that left at least one patient partially paralyzed.

Sanford Health settled a whistleblower lawsuit for $20 million in penalties last month. The hospital system was accused of allowing Asfora to defraud the government, but it denied wrongdoing or liability under the settlement.

Asfora has denied any wrongdoing.