Questions regarding Donald Trump’s relationship with Russia include, but are not limited to: why did the president of the United States leak confidential information about classified intelligence to Russian envoys? Why did that same U.S. president undermine his own U.N. ambassador by telling the Kremlin not to worry about the punishment she promised would be meted out for its actions in Syria? What was up with the president of the United States begging for Russia to be allowed back into the G7 after it was kicked out for invading another European country? And, of course: what’s the deal with Trump literally siding with Vladimir Putin over his own intelligence agencies, and generally behaving as though Vlad is his boss and paymaster? More recently, these questions have expanded to include members of Trump’s administration: for instance, lawmakers would also like to know why Trump’s Treasury secretary decided to lift sanctions on companies with links to Russian billionaire Oleg Deripaska, who just so happens to have strong ties to both Putin and Paul Manafort. By way of an answer, Steve Mnuchin told lawmakers to just “trust” the president when it comes to Russia. Now, however, Mnuchin himself has come under Congress’s microscope.

BuzzFeed News reports that California Representative Jackie Speier, a member of the House Intelligence Committee, sent a letter to Steve Mnuchin last week seeking information about a deal he reportedly struck in 2017 with Ukrainian-born U.S. billionaire Leonard Blavatnik who—wait for it—just so happens to be an associate of Deripaska’s. Writing that she has “serious concerns” about Mnuchin selling his shares in RatPac-Dune Entertainment to Blavatnik for roughly $25 million, she noted the move is “especially alarming” in light of a recent New York Times article reporting that Deripaska might have gotten something of a sweetheart deal from the Treasury:

Blavatnik, the letter notes, co-owns Sual Partners with another sanctioned oligarch, Viktor Vekselberg, and Sual “is a major shareholder” of Rusal, one of Deripaska’s sanctioned companies. It also notes that Blavatnik formerly served on Rusal’s board, and that one of his companies donated $1 million to Trump’s inaugural fund.

What a happy coincidence! While the congresswoman acknowledged that Mnuchin disclosed the sale at the time, she argued that the secretary’s relationship with a Blavatnik is “clearly a conflict of interest” given Mnuchin’s involvement in easing the sanctions. Speier goes on to ask for details related to the sale of the secretary’s RatPac shares, including the dates of the transactions and names of purchasers. She also requests to know whether Mnuchin “sought ethics guidance related to his involvement in the sanctions issue” and if “Blavatnik has tried to communicate with Mnuchin directly about the sanctions.”

The Treasury Department did not respond to BuzzFeed’s request for comment, and if we know ole Mnuch—and we think we do!—he’s unlikely to offer anything in the way of a satisfying explanation. Lawmakers have said his classified briefing to House members three weeks ago re: the decision to lift sanctions was “one of the worst classified briefings they had received from the administration.” He’s also made a name for himself over the past two years as one of Trump’s most reliable stooges, spinning an elaborate trickle-down fantasy re: how the president’s deficit-busting tax bill would pay for itself; defending Trump‘s praise of Nazis; routinely giving the president cover for the boldest of lies; and stonewalling any and all attempts by Democrats to get clarity when it comes to the Trump family’s financial entanglements. So it’s unlikely that he’ll all of a sudden come out and say, “You know what, you’re right, I’m totally compromised here and the president is, too.”