BOISE, Idaho (AP) — The Securities and Exchange Commission is suing a defunct Idaho investment firm, contending that two company officers purposely overbilled clients in a scheme to steal nearly $12 million.

The lawsuit filed in Idaho's U.S. District Court on Monday names Yellowstone Partners LLC and former CEO David Henry Hansen. Another defendant, investment adviser Cameron G. High, was also named in the lawsuit but has already reached a settlement with the SEC.

In the lawsuit, the regulatory agency says the defendants stole more than $11.8 million from over 120 client accounts, and that the money went to cover the company's operating expenses and to support Hansen's lavish lifestyle.

The alleged overbilling happened in several ways, the SEC said — by charging annual and quarterly fees too frequently to some clients, charging clients for additional services that were never provided, and charging some clients higher fees than they were supposed to be under their investment contracts.

The SEC is asking a judge to order Yellowstone Partners LLC, Hansen and High to give up any ill-gotten gains and pay fines.

The Idaho Falls-based company once had satellite offices around the West catering to wealthy clients in Idaho, Wyoming and Utah, but it closed last year in the wake of investigations by both the FBI and the SEC.

Both Hansen and High have also been criminally charged in separate cases. Hansen was indicted last year and charged with several counts of wire fraud and aiding and assisting in preparing fraudulent tax returns. He has pleaded not guilty and a trial is set for early next year.

High is scheduled to be sentenced next May for one count of wire fraud; he pleaded guilty and agreed to testify in Hansen's trial in a deal with prosecutors.

Hansen's attorney declined to comment, and an attorney for Yellowstone Partners LLC did not immediately return a phone call from The Associated Press. High's attorney declined to comment beyond noting that High has settled the SEC case.