A pair of Indiana doctors are accused of defrauding the state’s Medicaid program out of more than $1 million during the same time authorities say they were overprescribing painkillers that led to numerous patient overdoses and deaths.

Don and Marilyn Wagoner permanently surrendered their licenses to prescribe drugs and to practice medicine in 2013, following a state criminal investigation of their opioid-prescribing practices.

Now, federal authorities are pursuing the couple in civil court on accusations of filing 6,400 fraudulent Medicaid claims in order to overbill Indiana Medicaid by more than $1.1 million.

Working as physicians at their own clinics in Burlington and Kokomo, the Wagoners exaggerated the number of urine samples they collected and analyzed, according to a civil Medicaid fraud complaint filed Friday in U.S. District Court in the Northern District of Indiana. The filing was announced by Indiana Attorney General Curtis Hill and U.S. Attorney Thomas L. Kirsch II.

According to the complaint, the Wagoners filed false claims from 2011 to 2013, charging the program $171.27 per patient for collecting urine samples when Medicaid rules only allowed them to bill $20.83 per patient. The complaint alleges that the couple concealed the fraudulent charges by claiming to collect and analyze nine or more urine samples from each patient, when they were only collecting one sample per patient.

Federal and state laws allow authorities to try recover up to three times the amount of the false and fraudulent Medicaid claims, in addition to a civil penalty of $5,500 to $11,000 per false claim. If found guilty, the Wagoners could owe more than $70 million.

“Working to recover taxpayer funds taken through fraud and other illegal means is part of our responsibility as stewards of the public trust,” Hill said in a statement. “We appreciate the collaboration of our federal partners in this particular case, and we intend to remain vigilant going forward to make sure monies set aside to help society’s most vulnerable members are truly used for that purpose.”

The 2013 state criminal investigation of their opioid-prescribing practices resulted in felony drug-dealing convictions for Don Wagoner. The case against Marilyn Wagoner was dismissed last year, after a physician’s assessment found her unable to stand trial. At the time, she was living in an assisted living facility and suffering from mental incapacity, memory loss and declining cognitive functions.

“Although they no longer are endangering vulnerable Medicaid patients by practicing medicine, former physicians Don Wagoner and Marilyn Wagoner cannot be allowed to retain the fruits of their fraudulent Medicaid claims,” Kirsch said in a statement. “My office will continue to make it a priority to pursue investigations and cases to recover funds that were fraudulently received from the Medicare and Medicaid programs.”

The suit results from an investigation by the Indiana Medicaid Fraud Control Unit and the U.S. attorney’s office for the Northern District of Indiana.