Explosive new allegations from an FBI agent assigned to Special Counsel Robert Mueller’s investigation are raising fresh questions about how the high-profile probe into Donald Trump’s 2016 campaign was conducted.
According to a detailed account revealed in a letter from Senate Judiciary Committee Chairman Chuck Grassley, the agent claimed the Mueller team operated in a deeply biased environment where misconduct, political hostility toward Trump, and questionable investigative decisions were commonplace.
The allegations, first made during a December 2020 interview tied to an internal FBI probe, describe what the agent called a “Let’s get him” mentality that permeated the investigation. The probe into alleged collusion between the Trump campaign and Russia ultimately lasted nearly two years and cost taxpayers more than $30 million, but investigators concluded there was no evidence that Trump or his campaign conspired with Russia to influence the 2016 election.
Grassley outlined the whistleblower’s claims in a letter sent Sunday to Attorney General Pam Bondi and FBI Director Kash Patel, arguing the testimony reinforces long-standing concerns that political bias influenced decisions inside the special counsel’s office.
“The information provided by the whistleblower confirms long-standing concerns that political bias rotted the decision-making process within the Mueller team,” Grassley wrote. “The American public deserve answers.”
Among the most serious allegations are claims that investigators pursued cases despite lacking legal authority or sufficient evidence.
The agent said the Mueller team opened a case against billionaire businessman Tom Barrack — a close Trump ally and chairman of the 2017 inaugural committee — even after the FBI’s Washington Field Office declined to pursue the investigation. Barrack was later arrested and charged with acting as an unregistered agent of the United Arab Emirates.
After years of legal proceedings, Barrack was acquitted by a jury in 2022. He now serves as the U.S. ambassador to Turkey.
The whistleblower also alleged repeated misuse of federal surveillance authorities under the Foreign Intelligence Surveillance Act, or FISA. According to the account, investigators renewed surveillance warrants targeting Trump campaign advisers even when evidence suggested the targets were cooperating and no longer suspected of wrongdoing.
Mueller probe cut corners, broke rules to ‘get Trump,’ whistleblower claims An FBI agent assigned to then-Special Counsel Robert Mueller’s investigation into Donald Trump’s 2016 campaign has made bombshell allegations charging misconduct, political bias,… https://t.co/vt6BWnOWja pic.twitter.com/GG3RETLevk
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In one case, the agent reportedly warned colleagues that the surveillance had produced no evidence tying the target to alleged wrongdoing and had instead confirmed the individual was being truthful with investigators.
The allegations also involve former FBI lawyer Kevin Clinesmith, who later pleaded guilty to altering an email tied to a FISA warrant application involving Trump campaign adviser Carter Page. Clinesmith received 12 months of probation and briefly lost his law license before it was reinstated.
The whistleblower further claimed Mueller prosecutor Zainab Ahmad repeatedly violated security protocols by transporting classified materials improperly, including bringing a classified notebook from her residence to meetings at the FBI’s Washington Field Office.
Another allegation centers on former FBI Deputy Director Andrew McCabe. According to the whistleblower, McCabe used derogatory language about Trump during an official interview that was documented by investigators. Justice Department prosecutors allegedly later asked an FBI agent to soften the language in the official record, though the agent refused.
The account also describes an openly hostile workplace culture toward Trump inside the Mueller team’s offices. The agent said anti-Trump cartoons and caricatures were displayed on office walls and that some staff members consumed alcohol while on the job.
One prosecutor singled out in the claims was Aaron Zelinsky, who worked on several high-profile cases against Trump associates including Roger Stone and George Papadopoulos. Zelinsky resigned from the Justice Department in January 2025.
The renewed scrutiny comes after Special Counsel John Durham released a 2023 report concluding the FBI’s original Trump-Russia investigation was “seriously flawed.” Durham found investigators ignored or discounted evidence that contradicted the theory of a conspiracy between Trump and Russia.
Grassley has requested that the Justice Department and FBI provide emails, documents, and personnel records related to the whistleblower’s claims by March 29 as congressional investigators examine whether misconduct occurred during the Mueller probe.
