Michael Flynn, President Donald Trump’s embattled national security adviser, resigned late Monday after coming under fire for privately discussing U.S. sanctions against Russia before the presidential inauguration. The revelation, first reported by The Washington Post on Thursday, drew widespread criticism, but Flynn’s fall may have started with a separate casualty of the Trump administration: Sally Yates, the acting attorney general who was fired by the president last month.

Near the end of her short tenure at the head of the Justice Department, Yates reportedly informed the White House that Flynn may have misled senior officials about his calls with the Russian ambassador, according to reports from The Post, which cited unnamed officials:

The acting attorney general informed the Trump White House late last month that she believed Michael Flynn had misled senior administration officials about the nature of his communications with the Russian ambassador to the United States, and warned that the national security adviser was potentially vulnerable to Russian blackmail, current and former U.S. officials said. The message, delivered by Sally Q. Yates and a senior career national security official to the White House counsel, was prompted by concerns that Flynn, when asked about his calls and texts with the Russian diplomat, had told Vice ­President-elect Mike Pence and others that he had not discussed the Obama administration sanctions on Russia for its interference in the 2016 election, the officials said. It is unclear what the White House counsel, Donald McGahn, did with the information.

Those concerns were later echoed by James Clapper, President Barack Obama’s former director of national intelligence, and John Brennan, the former director of the CIA.

Yates made headlines at the end of January after announcing the Justice Department would refuse to defend Trump’s controversial executive order on immigration. She was fired within hours, and the White House released a strongly worded statement saying she had “betrayed” the administration.

Yates was widely praised for her decision. Former U.S. Attorney General Loretta Lynch said she “displayed the fierce intellect, unshakeable integrity, and deep commitment to the rule of law that have characterized her 27 years of distinguished service to the Department of Justice,” and former Sen. Barbara Boxer (D-Calif.) tweeted, “Thank God there are people who will follow the Constitution.”

Others called Yates a “profile in courage.”

Retired Lt. Gen. Keith Kellogg Jr. will serve as acting national security adviser until a full-time replacement is chosen. Four veteran strategists, including Kellogg, have already been suggested to fill the post.