Updated

Federal prosecutors in Tennessee say four family members have been convicted of running a multimillion-dollar Ponzi scheme centered on buying and selling gold and silver coins.

The U.S. Justice Department said Monday that Larry Bates; his sons, Chuck and Robert Bates; and Robert Bates' wife Kinsey, were found guilty of mail and wire fraud during a five-week trial in Memphis.

Prosecutors said the Bateses worked through First American Monetary Consultants, which had offices in Memphis and Boulder, Colorado. More than 360 people lost more than $21 million in the scheme, which lasted from 2002 through October 2013.

Customers gave $87 million to the company for the purpose of buying precious metals. But prosecutors said the Bateses kept money from the payments for their personal use.