CHICAGO—An Illinois man is facing multiple years in prison and must pay millions of dollars to former customers for a fraudulent investing scheme he carried out with a California man.

Roderick Rieman of St. Charles, owner of an insurance and investment business, was sentenced to four years in prison. Michael Crook of Los Angeles received a 31/2-year prison term. Both men were ordered to pay $6.6 million in restitution. They were sentenced in Chicago federal court on Wednesday.

Court documents show the men misrepresented investments and misappropriated funds to make "Ponzi-type" payments to investors.

According to the U.S. attorney's office, the men defrauded about 125 investors. Some victims lost some or all of their retirement or college savings.