Three accountants were sentenced this week in Utah to prison terms for a tax-fraud conspiracy involving offshore companies that cost U.S. taxpayers more than $20 million, the Justice Department said in a statement.

U.S. District Judge Tena Campbell sentenced the men, who pleaded guilty in federal court in Salt Lake City, for helping clients hide income from 1996 to 2005 from the Internal Revenue Service and for creating false tax deductions. The scheme involved offshore bank accounts in the Cayman Islands and Nevis, offshore nominee accounts and letters blessing the legality of phony transactions, according to the statement.

Campbell on Thursday sentenced Reed Barker to 18 months in prison and ordered him to pay $167,608 in restitution, according to the statement. On Wednesday, Campbell sentenced Stephen Peterson to 35 months and ordered him to forfeit $1.17 million. The judge also imposed a 24-month term on Brent Metcalf.

"These sentences send a firm message to tax professionals, especially accountants and CPAs, that if you assist your clients in defrauding the Internal Revenue Service, you will be punished to the fullest extent of the law," U.S. Attorney Brett Tolman said in the statement.

Peterson, of Coalville; Metcalf, of Cottonwood; and Barker, of Littleton, Colo., pleaded guilty in January. They were indicted in 2005 with three other people, including attorney Dennis Evanson, of Sandy, who was convicted at trial in February. He was sentenced last month to 10 years in prison and ordered to forfeit $2.78 million, as well as property and two cars.