A new bipartisan Senate investigation concluded Russian oligarchs have been using the opaque nature of the art industry to dodge U.S. sanctions, purchasing millions of dollars in art in an apparent money laundering scheme.

The 150-page report by the Permanent Subcommittee on Investigations, led by Chairman Rob Portman of Ohio and Vice Chairman Tom Carper of Delaware, detailed a two-year investigation providing a “case study” on how sanctions evasion can happen through the art industry — in this case by two wealthy Russians close to Russian President Vladimir Putin who were sanctioned by the Obama administration in response to Russia’s invasion of Ukraine and its annexation of Crimea.