A potential key witness in Robert Mueller’s investigation is firing back against the special counsel with a “criminal and ethics complaint.”

Conservative author Jerome Corsi slammed Mueller’s team in a complaint filed Monday alleging investigators tried to bully him into giving “false testimony” against President Donald Trump, Fox News reported.

“Dr. Corsi has been criminally threatened and coerced to tell a lie and call it the truth,” the 78-page document asserted, noting a “slow-motion coup against the president.”

The author of the anti-President Obama book “The Obama Nation” refused to strike a plea deal with Mueller’s team, threatening that he would file the complaint for several days before Monday as tensions have escalated with the special counsel’s attempt to play hardball with targets of the probe.

Mueller’s office was accused of “knowingly and deceitfully threatening to charge Dr. Corsi with an alleged false statement,” unless he provided “false testimony” against Trump and others, Fox News reported.

The complaint alleged that investigators were attempting to get Corsi to show how he linked political operative Roger Stone and WikiLeaks founder Julian Assange with the Trump campaign in connection with the release of hacked Democratic National Committee emails.

According to Fox News:

The purported threat of a false statement charge, according to the complaint, pertains to a July 2016 email from Stone asking him to “get to” Assange and get the pending emails. Corsi’s complaint says he was unable to initially give “accurate” testimony on that point, until he could reload emails on his laptop. The complaint says he later amended his answers. In an interview last week with Fox News’ “Tucker Carlson Tonight,” Corsi said Mueller’s team “was happy” with his answers until he couldn’t “give them what they wanted.”

Portions of Corsi’s grand jury testimony appeared to contradict what Stone said he knew about the WikiLeaks plans during the 2016 campaign. Mueller’s proposed plea agreement for Corsi noted the email exchanges between the author and Stone, a Trump confidant.

Lawyers for the author of the upcoming book, “Silent No More: How I Became a Political Prisoner of Mueller’s ‘Witch Hunt,’” denied allegations that Corsi was colluding with Assange or had any inside information.

“Employing his professional skills and considerable experience as an analyst and investigative journalist, Dr. Corsi logically concluded that WikiLeaks would release Podesta’s emails soon in a second round ‘data dump’ from the same group of DNC emails stolen on July 5, 2016,” Monday’s complaint read.

The complaint follows last week’s revelation that the special counsel’s office had struck a plea deal with former Trump personal attorney Michael Cohen who pleaded guilty to lying to Congress. Former Trump campaign chairman Paul Manafort was also accused last week of lying to investigators and thereby breaking his plea agreement.

Trump continued his criticism of Mueller’s probe and tweeted that the special counsel is “a much different man” than people think he is.

Bob Mueller (who is a much different man than people think) and his out of control band of Angry Democrats, don’t want the truth, they only want lies. The truth is very bad for their mission! — Donald J. Trump (@realDonaldTrump) December 3, 2018