Former CIA Director John Brennan has been subpoenaed to testify next month before a Florida grand jury as part of a Justice Department investigation into whether former law enforcement and intelligence officials conspired against President Donald Trump.

Ken Wainstein, an attorney for Brennan, disclosed in a court filing Monday that prosecutors last Thursday presented him with a subpoena for Brennan to appear Oct. 15 before a grand jury in Fort Pierce, Florida.

He said he was told that the subpoena relates to a "far-reaching" criminal probe examining whether government officials who have investigated Trump over the past decade conspired to deprive Trump of his civil rights.

According to Wainstein, a prosecutor also informed him that Brennan remains a target in a separate Washington-based investigation examining whether he lied to Congress in 2023, an allegation Brennan and his legal team have consistently denied.

The development comes amid leadership upheaval within the probe. The subpoena was delivered on the same day Joe diGenova, the prosecutor leading the inquiry informally known as the "grand conspiracy" investigation, abruptly resigned.

The Justice Department has not publicly named a replacement for diGenova. Wainstein said he spoke with Kurt Olsen, a member of the investigative team and a lawyer who urged the Justice Department in 2020 to back Trump's claims that the election had been stolen.

Disclosure of the subpoena came hours ahead of a scheduled court hearing in Washington concerning a lawsuit brought by Brennan.

The former CIA chief is seeking a court order to preserve all records related to the investigations targeting him, arguing the documents are essential to challenge any potential indictment on grounds of vindictive prosecution.