D.C. insurance regulators said Friday that the longtime city contractor at the center of a major campaign finance scandal owes his former company -- one that the District placed into receivership last year -- about $3.9 million.

In a court filing, the District said that a holding company controlled by Jeffrey Thompson owes Chartered Health Plan, the Medicaid managing care provider D.C. now oversees, $2.8 million in federal tax refunds.

The city also demanded that the holding company produce "appropriate documentation" for more than $1 million in payments to a linked corporation. If Thompson's company doesn't provide the records, the District said the holding company would be asked to pay the money.

The District also said it remains in negotiations with Philadelphia-based AmeriHealth about a purchase of Chartered, which provides health coverage to about 110,000 District residents.

"We are working with a willing partner here to try and get this done, so we're hoping we can complete something sooner rather than later," said William White, the commissioner of the D.C. Department of Insurance, Securities and Banking.

The District took control of Chartered Health last year after an audit found "financial irregularities," though White said those troubles had not affected the company's care programs.

"The providers have continued to be paid for their services, and the enrollees have continued to receive those services," he said.

Although Chartered has not been implicated, Jeffrey Thompson is the subject of an expansive federal investigation focused on campaign finance practices in the District.

Thompson was for years the city's largest contractor and a prolific campaign donor, though he has all but disappeared from the District's political landscape since the FBI searched his home and offices last year.

People familiar with the federal investigation have said that Thompson financed an illegal shadow campaign that helped elect Mayor Vincent Gray, who has denied wrongdoing.

Thompson has not been charged with any crime, but a longtime associate pleaded guilty last July to her role in the shadow campaign.

Thompson's attorney has not responded to repeated requests for comment.