John Brennan Has Been Subpoenaed to Testify Before a Fort Pierce Grand Jury on Oct. 15 in the 'Grand Conspiracy' Probe. The Prosecutor Who Signed It Quit the Same Day.

Former CIA Director John Brennan has been ordered to appear before a federal grand jury in Fort Pierce, Florida, on Oct. 15 as part of the Justice Department's sprawling "grand conspiracy" investigation into officials who investigated Donald Trump over the past decade, his attorney disclosed in a court filing on Monday. The subpoena was delivered last Thursday, according to the filing by Ken Wainstein, Brennan's lawyer, and was reported by The Associated Press.

The Fort Pierce probe is examining a theory advanced by Trump and his allies that government officials who pursued him, from the 2016 Russia election-interference inquiry through the 2022 investigation into classified documents kept at his Mar-a-Lago estate, conspired to deprive him of his civil rights. Wainstein wrote that a prosecutor described the investigation as "far-reaching." Fort Pierce is the seat of the federal courthouse where U.S. District Judge Aileen Cannon dismissed the Mar-a-Lago documents case against Trump in 2024. Justice Department lawyer Kurt Olsen is on the investigative team.

The subpoena was signed by Joe diGenova, the veteran Trump loyalist who had been leading the conspiracy investigation, according to NBC News. The AP reported that the disclosure came on the same day diGenova abruptly resigned amid displeasure inside the Justice Department and the White House over the pace and management of the probe. In April, a different prosecutor withdrew from the Trump team's investigation of Brennan, one of several personnel changes that have dogged the effort.

Wainstein also revealed that Brennan remains a target in a second, Washington-based investigation into whether he lied to Congress in 2023. That inquiry stems from Brennan's testimony that the CIA did not rely on the Steele dossier when it prepared the January 2017 Intelligence Community Assessment on Russian interference. House Judiciary Committee Chairman Jim Jordan referred Brennan to the Justice Department over that testimony last year, and Fox News reported in November 2025 that prosecutors in Miami and Washington were preparing grand jury subpoenas under the supervision of Jason Reding Quiñones, the U.S. attorney for the Southern District of Florida. Grand jury subpoenas in the false-statements probe were issued in the spring, then withdrawn in favor of voluntary interviews. Brennan and his lawyers have consistently denied that he lied.

Brennan, who ran the CIA from 2013 to 2017 under President Barack Obama, has been one of Trump's most persistent critics and one of the names Trump most often invokes when describing what he calls the "Russia hoax." Former FBI Director James Comey, another frequent target, was indicted last year on false-statement and obstruction charges. Unlike a target letter, a grand jury subpoena compels testimony; Brennan could invoke the Fifth Amendment, but doing so would hand the administration a political talking point it has been seeking for years.

The Justice Department did not immediately comment on the subpoena or on diGenova's departure. Whether the investigation survives the loss of its lead prosecutor, and whether a Fort Pierce grand jury ultimately returns any charges, are now open questions with five weeks to go before Brennan's scheduled appearance.