Former CIA Director John Brennan has been subpoenaed to testify before a Florida grand jury as part of a Justice Department investigation into an alleged conspiracy against President Donald Trump.

The investigation is examining former government officials involved in investigations and intelligence assessments that Trump has argued unfairly targeted him.

Brennan’s lawyer confirmed the subpoena and said he is expected to appear before the grand jury next month.

The inquiry is part of a broader Justice Department investigation that has issued subpoenas to several former intelligence and law-enforcement officials, The Guardian has reported.

No charges have been filed against Brennan, and the investigation remains ongoing.