An FBI agent who was present at the “ambush interview” of General Michael Flynn is ready to testify in defense of President Trump’s former National Security Advisor.

If subpoenaed, Special Agent Joe Pientka will speak to members of the Senate Judiciary Committee about the circumstances surrounding the interview of Flynn in January 2017, according to investigative reporter, Sara Carter.

Pientka had joined in that interview with embattled FBI Special Agent Peter Strzok, who was later removed from Special Counsel Robert Mueller’s investigation of Trump’s campaign after text messages were found between him and former FBI attorney Lisa Page, with whom he was having an affair.

Senate Judiciary Chairman Chuck Grassley revealed Pientka’s name in a letter earlier this month to Deputy Attorney General Rod Rosenstein and FBI Director Christopher Wray demanding the FBI and the Justice Department hand over the transcript of Flynn’s intercepted calls with former Russian Ambassador Sergey Kislyak.

Classified information from those calls were leaked to the Washington Post last January, sparking the controversy which eventually led to Flynn’s firing by the White House in February 2017. Former FBI Director James Comey said on several occasions that he did not believe Flynn had lied during the interview, though the fired official later denied having said any such thing, according to Carter’s report.

According to Carter:

It’s this reporters understanding that Pientka will account for what Flynn said in the interview and will give context to the FBI’s accusation that he lied during the interview. If asked, Pientka will also give his personal opinion as to whether or not that was actually the case. He will also discuss how forthcoming Flynn was about very specific sensitive information that Flynn could not have possibly known the investigators already knew, which may give additional insight into Flynn’s veracity and willingness to tell the truth. Pientka, however, will only testify about the circumstances regarding the Flynn interview and the issues that pertain to that interview, according to two sources with knowledge. There is no reason to believe that Pientka has any information on Comey’s role in the Trump Russia investigations but wants the opportunity to “state the truth” what has been said about Flynn, said the source, with direct knowledge.

Grassley revealed in his letter that another “non-partisan law enforcement officer” was present during the interview with Flynn and his notes indicated that “Comey specifically told us during that briefing that the FBI agents who interviewed Lt. General Michael Flynn, ‘saw nothing that led them to believe [he was] lying.'”

Pientka isn’t the only FBI official willing to testify, according to Carter.

“There are roughly 20 plus former and current FBI personnel who are prepared to be subpoenaed in an effort to unveil the truth about the Bureau’s investigation into both President Donald Trump’s campaign, as well as the bureau’s handling of Hillary Clinton’s use of a private email server to conduct government business, according to numerous sources who’ve spoken to this reporter,” she wrote.