Bonds sold to purchase the River Park Square garage are not tax-exempt because the groups involved in the deal did not follow federal law, paid an unreasonably high amount for the facility and gave too much money to the mall's private developer, an Internal Revenue Service report says. A final Proposed Adverse Determination report, received this week by the city of Spokane from an IRS supervisor in Denver, is scathingly critical of the deal that involved the city, affiliates of Cowles Publishing Co. that renovated the downtown mall, and a foundation that sold bonds to buy the garage for $26.5 million. It says one part of the project "raises troubling aspects of potential fraud" and refers to some of the complicated financing as "smoke and mirrors."