Michael Flynn, President Donald Trump’s disgraced former national security adviser, may be in even more legal hot water.

CNN reports that House Democrats have sent special counsel Robert Mueller evidence that Flynn failed to disclose that, in 2015, he helped broker a $100 billion deal between the government of Saudi Arabia and a Russian state-owned company.

According to a letter signed by Reps. Elijah Cummings (D-MD) and Eliot Engel (D-NY), Flynn never disclosed his role in brokering the deal when he reapplied for his national security clearance upon returning to the United States after his trip to the Middle East in 2015. Additionally, Flynn never disclosed that he received a payment of $25,000 for his work in lobbying for the deal.

“It appears that General Flynn violated federal law by omitting this trip and these foreign contacts from his security clearance renewal application in 2016 and concealing them from security clearance investigators who interviewed him as part of the background check process,” the letter reads.

Flynn’s attorneys are refusing to comment publicly on the allegations, and they are also telling House Democrats that their client will not respond to their inquiries unless legally compelled to do so.