Evidence withheld for years from Michael Flynn's defense team shows the FBI found "no derogatory" Russia evidence against the former Trump National Security Adviser and that counterintelligence agents had recommended closing down the case with a defensive briefing before the bureau's leadership intervened in January 2017.

The recommendation to close the case came 16 days before President Trump took office with plans to have Flynn serve as his National Security Adviser, and after agents had found no incriminating evidence by sweeping counterintelligence files and talking to confidential human sources, the memos show.

Flynn was given a codename of "Crossfire Razor" during the probe, an apparent spinoff from the larger Russia collusion case known as Crossfire Hurricane.

"The absence of any derogatory information or lead information from these logical sources reduce the number of investigative avenues and techniques to pursue. Per the direction of FBI management, Crossfire Razor was not interviewed as part of the case closing procedure. The FBI is closing this investigation," the agent wrote on Jan. 4, 2017.

The release of the memo Thursday is the result of extraordinary efforts by Attorney General William Barr to bring transparency to a case that dogged the beginning of the Trump presidency and has since dissolved into controversy over the FBI conduct during it. Barr has named a special prosecutor to review the bureau's handling of Flynn and determined if any criminal charges are warranted.

You can read the case close memo here.

The files show the plan was to provide Flynn with a defensive briefing so he could be aware of potential pitfalls with Russians as he started in his new job in the White House. But then the lead agent in the larger Russia case, Peter Strzok, intervened to stop the case from being closed and pivoted the discussion toward seeking an interview with Flynn, FBI text messages show.

In the text messages to his team, Strzok specifically cited "the 7th floor" of FBI headquarters, where then-Director James Comey and then-Deputy Director Andrew McCane worked, as the reason he intervened.

"Hey if you haven't closed RAZOR, don't do so yet," Strzok texted on Jan. 4, 2017.

"It is still open and I'm still listed as the case manager," his colleague texted back.

"Rgr, I couldn't raise earlier. Please keep it open for now," Strzok texted. Later he added, "7th floor involved."

The text messages show the discussion pivoted from closing the case to seeking an interview with Flynn, and suggest there was a dispute between McCabe and his top counterintelligence official, Assistant Director William Priestap, who appeared to be concerned the FBI was being unfair to Flynn.

"About Bill. He was pretty adamant about what Andy it [sic] said with regard to that," Strzok texted Lisa Page, then a lawyer working for McCabe. "And he mentioned on Saturday that he had several conversations with Andy. Bill sense with it [sic] and he wanted to know why he had to go aggressively doing these things, openly. I worry Bill isn't getting the underlying distinction that I think is clear but maybe I'm wrong."

Strzok's followup text messages suggest Priestap went to Director Comey (referred to as D) because of his concerns about McCabe's approach.

"Bill just told [deleted) and me that he brought up again, this time in front of D — didn't know he was going to D on that," Strzok texted.

Page texted back that her boss, McCabe, appeared to be upset.

"Yeah, DD is frustrated. Going into meeting. Don't repeat," she texted back.

"I won't. Bill said D started going one way and DD cut him off," Strzok wrote. "I'd be frustrated too."

You can read the text messages here.

Handwritten notes that a federal court released Wednesday show Priestap harbored concerns that the FBI was "playing games" with the Flynn investigation and may have been trying to use the interview to "get him to lie, so we can prosecute him or get him fired?" Just the News reported.

It was that late January 2017 interview conducted by Strzok and another agent that resulted in the former Trump National Security Adviser resigning and eventually pleading guilty to lying in the interview.

Flynn has since retained new counsel, Sidney Powell, and sought to vacate his conviction on grounds that the new evidence shows an effort by the FBI to "frame" him for a crime he did not commit.