EDITOR'S NOTE: This story is an update of a CNN report that published in January . It has been updated to include new information.

(CNN) Former acting Attorney General Sally Yates will testify Monday before a Senate Judiciary subcommittee on Russia's meddling in the US election last year, the latest public event in a political saga that has spanned President Donald Trump's young presidency.

Yates became a household name after Trump fired her in January after she refused to defend his immigration order.

"The acting Attorney General, Sally Yates, has betrayed the Department of Justice by refusing to enforce a legal order designed to protect the citizens of the United States," White House press secretary Sean Spicer said in a statement explaining the President's action.

But the former Justice Department official re-entered the news cycle a week after her firing when a White House official confirmed that Yates warned the Trump administration earlier in the month that former national security adviser Michael Flynn misled administration officials about his communications with Russia before his entering the White House.

Sources familiar with Yates' account told CNN last week that she is prepared to testify at the hearing that she gave a forceful warning to the White House about Flynn nearly three weeks before he was fired, contradicting the administration's version of events, including that of Spicer, who said in February that Yates had simply "wanted to give a 'heads up' to us on some comments that may have seemed in conflict with what he (Flynn) had sent the Vice President."

Intelligence agencies said Flynn had spoken to the Russian ambassador to the United States about sanctions imposed by former President Barack Obama and was potentially vulnerable to blackmail by the Russians, a person familiar with the matter told CNN.

Other top intelligence officials, including Director of National Intelligence James Clapper and CIA Director John Brennan, were in agreement with Yates that the White House should be alerted about the concerns.

On Saturday, a former US official told The Washington Post and CNN that members of Trump's transition team alerted Flynn in November, weeks before his conversation with Russian Ambassador Sergey Kislyak took place, that any conversations with Kislyak were most likely being monitored.

Flynn, who was not in the administration at the time of the talks, resigned his position in February shortly after the reports emerged.

Appointed by Obama, Yates had been running Trump's Justice Department while attorney general nominee Sen. Jeff Sessions awaited confirmation. Before that, she spent years defending Obama administration policies, championing changes to the criminal justice system and curtailing the federal government's use of private prisons.

But when Yates told Justice Department lawyers not to make legal arguments defending Trump's executive order on immigration and refugees, she was thrust into the biggest controversy of the opening days of Trump's presidency.

"My responsibility is to ensure that the position of the Department of Justice is not only legally defensible, but is informed by our best view of what the law is after consideration of all the facts," Yates said in a letter to department lawyers.

Hours later, she was gone, a dramatic end to her lengthy career at the department.

Georgia roots

Born in Atlanta in 1960, Yates attended the University of Georgia both as an undergrad and a law student, becoming what the home of the Bulldogs calls a "double dawg."

Three years after graduating from UGA, she began a career in the Justice Department that spanned almost three decades, according to her DOJ biography page.

Deputy Attorney General Sally Q. Yates speaks during a press conference at the Department of Justice on June 28, 2016 in Washington, DC.

Yates started there at the end of the 1980s, working as an assistant US attorney in the Northern District of Georgia. She worked her way up in a series of cases the DOJ described as including white-collar fraud and political corruption.

In 1996, Yates aided the prosecution of Eric Rudolph, who pleaded guilty to bombing Centennial Olympic Park in downtown Atlanta during the Olympic ceremonies.

In 2010, Obama appointed her to run the local US attorney's office, the first time a woman had reached the position there.

She subsequently climbed the DOJ ladder almost to the very top. When former Attorney General Eric Holder informed Obama of his intention to leave the office, Obama tapped Loretta Lynch for attorney general and Yates for deputy.

Unlike Lynch, who faced a divided Senate for confirmation, Yates made it through her Senate grilling with wide, bipartisan support. Georgia Sens. Johnny Isakson and David Perdue -- both Republicans -- spoke on her behalf.

She did face some pushback from conservative corners, however. Sessions, an Alabama Republican, was among those to question her sharply during her Judiciary Committee hearing, and he ultimately voted against her confirmation.

That final step highlights the irony of the Trump administration asking Yates to stay on as attorney general after the inauguration until Sessions, Trump's nominee, could take over.

Yates accepted the request, and that meant Trump would have someone leading DOJ who was well outside of his ideological mold.

The clash that followed was set up by Trump's decision to move ahead with the immigration executive order -- suspending the refugee program and temporarily halting travel from seven predominantly Muslim countries -- before Sessions was installed.

The day after Trump issued the order, a federal judge blocked part of it. More legal challenges mounted, and Yates instructed the department not to defend the administration against them.

Then, in January, she was hand-delivered a letter from the White House that ended her Justice Department career.