“The declarations are detailed, and span numerous topics that arose during Covington’s 30-month representation of Mr. Flynn,” Ballantine wrote. “The government needs additional time to review these declarations and to determine whether it needs to conduct any interviews of Covington personnel or to seek additional declarations or supporting documents.”

The Justice Department’s response to Flynn’s motion is being closely watched for any signs that Attorney General William Barr or other department officials endorse the former White House aide’s claim that he was railroaded by the FBI and prosecutors as part of a corrupt effort to bring down President Donald Trump.

President Donald Trump has repeatedly complained that Flynn was unfairly targeted by top FBI officials. Earlier this week, Trump again called those officials “human scum.”

So far, the Justice Department has defended the case against Flynn and has successfully opposed Flynn’s motions for wide-ranging access to records about the origins of the probe into the Trump campaign and Russia, as well as a variety of other matters.

However, in January, Barr assigned the U.S. attorney in St. Louis, Jeff Jensen, to review the handling of the Flynn case by prosecutors and the FBI.

On Friday, prosecutors also sent Flynn’s lawyers some FBI material Jensen has pulled into his review. The handoff, which was made public in a separate court filing, seems like a victory for the Flynn defense team’s sustained drive to get broader access to records related to the investigation.

The actual records were not made public, but Flynn’s defense lawyers were also told Friday that they might receive more information as Jensen’s review progresses.

Powell did not immediately respond to a request for comment for this story, but in a court filing she called "stunning" the evidence just handed over by the Justice Department. In a tweet earlier Friday, she welcomed the new documents emerging from Jensen's review.

"The government just provided the #Flynn defense with remarkable new & long withheld BRADY evidence," she wrote, referring to a Supreme Court decision requiring prosecutors to turn over evidence that might undermine the prosecution. "Stay tuned."

Jensen, a former FBI agent, has not filed a formal court appearance in the case.

The lead prosecutor of Flynn for Mueller’s office, Brandon van Grack, is now a senior Justice Department official overseeing foreign influence matters and he remains assigned to the case. However, his name has not appeared on recent pleadings about Flynn’s claims faulting his previous counsel. Van Grack could be a witness on that issue because of his dealings with those lawyers when Flynn’s plea was being negotiated.

Flynn's current defense team lashed out at Van Grack on Friday, accusing him of threatening Flynn's son, Michael Flynn Jr., with prosecution, then cutting an off-the-record deal to go easy on the son if the elder Flynn pleaded guilty. (The younger Flynn was never charged.)

"Mr. Flynn’s counsel has found further evidence of misconduct by Mr. Van Grack specifically," Powell wrote. "The government’s misconduct in this case is beyond shocking and reprehensible."

Powell filed with the court Friday heavily redacted internal emails from Covington lawyers Robert Kelner and Stephen Anthony about the possible impact of a Flynn plea on his son.

"We have a lawyers' unofficial understanding that they are unlikely to charge Junior in light of the Cooperation Agreement," Kelner wrote in a March 2018 message to Anthony. A little over a week later, Anthony sent an email to Kelner and others saying prosecutors did not want to make an explicit pledge not to prosecute Flynn's son because it could undermine the father's testimony if he later took the stand for the government.

"The government took pains not to give a promise to MTF regarding Michael Jr., so as to limit how much of a 'benefit' it would have to disclose ... to any defendant against whom MTF may one day testify," Anthony wrote.

After coming under scrutiny from the FBI and special counsel Robert Mueller’s office, Flynn struck a deal to plead guilty to a single felony false-statement charge stemming primarily from comments he made to FBI agents in January 2017 about his dealings with the Russian ambassador to the U.S. and other matters.

A judge accepted Flynn’s guilty plea in October 2017. Before and after that, Flynn cooperated extensively with prosecutors and investigators, taking part in about 20 interviews on various topics.

Last spring, Flynn parted company with his legal team — led by Kelner and Anthony — and signed on with new counsel, led by Sidney Powell, a Texas attorney and prominent Mueller critic. She wrote to Barr to demand a top-to-bottom review of the investigation and prosecution.

The Flynn team’s relationship with prosecutors soon soured. The government dropped plans to call Flynn at a criminal trial last summer of Flynn’s former business partner, Bijan Rafiekian.

Flynn’s new lawyers eventually demanded about 50 categories of documents, but U.S. District Judge Emmet Sullivan issued an opinion last December sharply rejecting those requests as either superfluous or irrelevant.

Flynn’s new legal team then escalated its campaign against the prosecution, making a high-stakes gamble by moving to formally withdraw his plea. The step opened Flynn to potential prosecution on other charges for breaching his plea agreement, although Flynn’s attorneys claim prosecutors had already blown up the deal by stepping back from earlier suggestions that probation would be an appropriate sentence for the former Defense Intelligence Agency chief.

Prosecutors insisted they never changed their position that probation would be a reasonable sentence, as would a prison term of up to six months, but the shifting tone of prosecution filings in the case again prompted speculation about intrigue at the Justice Department.

Sullivan has indefinitely postponed Flynn’s sentencing while the maneuvering around his motion to withdraw his plea continues. It has been 2½ years since Flynn pleaded guilty.

After the government filing Friday, Sullivan approved the prosecution’s request to submit another update by May 8 about how it plans to respond to Flynn’s motion to withdraw his plea.