By Katelyn Polantz, CNN

(CNN) -- Michael Flynn, President Donald Trump's former national security adviser, is turning to a lawyer who fanned conspiracy theories about investigators' conduct in his case to represent him as he awaits sentencing.

Sidney Powell, a Texas-based former federal prosecutor and conservative-leaning political commentator, will represent Flynn after he fired his long-time legal counsel, from the large Washington law firm Covington & Burling, according to two sources familiar with the development. Powell has not yet announced in court that she will represent Flynn.

The Hill first reported on Wednesday that Powell would represent Flynn.

Powell will be tasked with helping Flynn through what may be a contentious trial this summer against his former lobbying partner where he will likely be a witness for the prosecution, and with attempting to win a judge's sympathy at his sentencing after a disastrous hearing last December.

Powell and her law firm did not respond to multiple requests for comment from CNN this week. Lawyers from Covington & Burling have also declined to comment. In a statement to Axios, Powell said she is "honored" to represent Flynn and he would continue to cooperate with the government.

A former federal prosecutor based in Texas, Powell has become known in recent years for her criticism of the Mueller investigation, especially on Fox News. She wrote a book focused on alleged prosecutorial misconduct in past major investigations -- including the case against the late Alaska Sen. Ted Stevens, which Judge Emmet Sullivan dismissed because of how prosecutors had handled the case.

In an op-ed before Flynn's aborted sentencing hearing last December, Powell pushed the idea that Flynn may not have received all of the relevant information in his case from prosecutors and the FBI, citing a law that requires defendants to see all information, which Flynn did after his plea because of the judge's order.

"Mueller has shown abject contempt for the wrong court. Judge [Emmet] Sullivan is a real judge who believes in the rule of law and has the integrity to enforce it equally," Powell wrote in an op-ed in The Daily Caller. "The evidence strongly suggests Mueller violated Brady, destroyed or suppressed evidence, and obstructed justice. He has disgraced himself and the Department of Justice. Mueller's time is up."

At the sentencing hearing, Sullivan harshly rejected a possibility that Flynn may not have accepted his responsibility after pleading guilty, even after Mueller's team gave him a glowing recommendation for little to no jail time. Sullivan accepted his guilty plea in open court in December, then Flynn asked to delay sentencing so he could continue to help prosecutors with their investigations.

The sentencing has not been rescheduled.

This story is breaking and will be updated.