An attorney representing Russian oligarch Oleg Deripaska has refused to tell Senate investigators what he knows about dossier author Christopher Steele’s financial and business relationships with the Russians. Steele is the former British intelligence agent hired by Democrat research firm Fusion GPS on behalf of the Democratic National Committee and Hillary Clinton campaign.

Sen. Charles Grassley (R-Iowa) sent a letter Feb. 9, 2018, asking Paul Hauser whether he was legal counsel for Deripaska or any businesses associated with him. He also asked whether he’d ever hired Steele or his businesses, and what the nature of the arrangement was. He asked whether and when Steele worked on behalf of Deripaska. Finally, he was asked, “Are you otherwise aware of any business or financial relationships between Mr. Steele and Russian government officials, Russian oligarchs, or Russian businesses?”

Hauser refused to answer all but the first question. In a letter written Feb. 18 but made public this week, he admitted he is legal counsel for Deripaska and businesses associated with him. He refused to answer whether Deripaska had hired Steele and to answer what he knows about Steele’s financial relationships with Russian government officials, oligarchs, or businesses. He said he wasn’t involved with the dossier and that he’s not aware of Deripaska commissioning, paying for, or preparing the dossier.

Congressional investigators aren’t just interested in determining whether Steele ever took payments from or worked on behalf of Russian individuals or organizations. They are also reportedly interested in whether Deripaska or his associates were sources for the document, more than whether he commissioned, paid for, or prepared it.

Sen. Lindsey Graham (R-S.C.) and Grassley wrote a lengthy letter to the inspector general of the Department of Justice (DOJ) March 15, 2018, demanding to know whether Steele was ever paid by Russian sources in or out of the government.

“What connections are there between Mr. Steele and the Russian government or Russian intelligence community?” the senators asked. “Has Mr. Steele ever been paid directly or indirectly by the Russian government, Russian intelligence community, or other Russian sources?”

Steele’s relationship to questionable Russian figures became public when encrypted text messages between Sen. Mark Warner (D-Va.) and Adam Waldman, a registered foreign agent for Deripaska, were leaked to the media. In those texts, Waldman repeatedly tried to broker access between Steele and Warner, the vice chairman of the Senate Intelligence Committee. It remains unclear why a registered foreign agent for a Russian oligarch would be running interference for Steele.

The letter to DOJ from Graham and Grassley, who chairs the Senate Judiciary Committee, appears to be the first formal demand of the DOJ inspector general to disclose whether the author of a dossier that alleged nefarious connections between Donald Trump and the Russians was himself a tool of the Russian government, its intelligence community, or its oligarch allies.

Fusion GPS, a firm the Clinton campaign hired through its lawyers, also has well-known ties to shady Russian firms and officials, as it was hired on behalf of a Russian firm accused of evading U.S. sanctions. Bill Browder is a well-known anti-Putin whistleblower and activist whose attorney, Sergei Magnitsky, was killed in Russian custody, leading to the U.S. enactment of sanctions against Russia. He has accused Fusion GPS of illegally serving as an unregistered foreign agent for Russian individuals and institutions.

Sean Davis contributed to this report.