Former CIA Director John Brennan has been ordered to appear before a federal grand jury in Fort Pierce, Florida, on Oct. 15 — the latest and highest-profile move yet in a sprawling Justice Department investigation examining whether officials who scrutinized Donald Trump over the past decade broke the law by conspiring against him.

Brennan's attorney, Ken Wainstein, disclosed the subpoena in a court filing made public Monday, revealing that prosecutors handed Brennan the summons the previous Thursday. He is not alone: a federal grand jury also subpoenaed two central figures from the FBI's 2016 "Crossfire Hurricane" probe — former counterintelligence official Peter Strzok and former FBI lawyer Lisa Page — with sources telling reporters that as many as 30 total subpoenas could ultimately go out in the case.

Two Probes, One Target

The Fort Pierce subpoena stems from what investigators informally call the "grand conspiracy" case: a far-reaching inquiry into whether Obama- and Biden-era officials worked together to deprive Trump of his civil rights by pursuing the 2016 Russia-interference investigation and, later, the classified-documents case at Mar-a-Lago. Brennan is described as a "subject" of that broader probe. He is separately named a "target" — a more serious legal designation — in a narrower Washington-based investigation into whether he lied to Congress about how the intelligence community assessed Russian election interference, a matter tied to a referral from current CIA Director John Ratcliffe over the handling of the Steele dossier.

The subpoena itself was signed by prosecutor Joe diGenova, who days later abruptly resigned from the case amid what officials described as growing friction among senior Justice Department leaders over how the investigation is being managed. Prosecutor Kurt Olsen, who unsuccessfully pushed the department in 2020 to pursue election-fraud claims, remains on the team and was the one who delivered the subpoena to Wainstein.

"A blatantly unconstitutional effort to target an innocent man," Wainstein said of the investigation in the court filing.

Brennan, who led the CIA from 2013 to 2017 and has been one of Trump's most persistent critics since leaving office, has not been charged with a crime. His legal team has gone on the offensive, filing suit to force the preservation of all investigative records and laying groundwork for a potential vindictive-prosecution claim should charges ever materialize.

DiGenova's exit is not the first sign of turbulence inside the office running the case. The investigation is based out of the U.S. Attorney's office for the Southern District of Florida, led by Trump-appointed U.S. Attorney Jason Reding Quiñones, which has already seen career prosecutors resign rather than take part in the sprawling inquiry, according to earlier reporting on the office's internal churn.

For now, the calendar is set: Brennan is due in Fort Pierce on Oct. 15, though it remains unclear whether he will testify, invoke constitutional protections, or seek to fight the subpoena in court before then. With the prosecution team in flux and additional subpoenas reportedly still going out, the scope of the "grand conspiracy" investigation — and how far up or down the chain it ultimately reaches — is likely to keep expanding in the weeks ahead.