Federal prosecutors in Florida have issued a grand jury subpoena requiring Daniel C. Richman, a close associate of former FBI Director James B. Comey, to testify, according to a person familiar with the matter.
The subpoena was issued by prosecutors in the US attorney’s office for the Southern District of Florida and appears to be linked to a broader investigation seeking to establish an alleged conspiracy involving Comey and other former federal officials who investigated President Donald Trump.
The development represents a notable escalation in the Florida investigation, which has increasingly focused on individuals associated with Trump’s political opponents. Comey has already been indicted in two separate cases in Virginia and North Carolina.
It is not yet clear what information prosecutors are seeking from Richman, a Columbia University law professor who previously served as an adviser to Comey during his tenure at the FBI.
Richman has previously been questioned in investigations involving his former boss and friend. One investigation, which concluded without criminal charges, examined whether Comey had used Richman to pass information about sensitive FBI investigations to journalists.
A separate investigation resulted in an indictment against Comey last September over allegations that he lied to Congress concerning matters related to the same leak inquiry.
The Justice Department did not respond to an email requesting comment on the latest subpoena.
The Florida investigation marks the third occasion on which Richman has been asked to provide information concerning Comey.
The inquiry is being overseen by Joseph diGenova, a prominent Trump ally, who has convened a grand jury in the US District Court in Fort Pierce. The proceedings are being supervised by Judge Aileen M. Cannon, a Trump appointee.
The investigation has also turned its attention to other former officials who have drawn Trump’s criticism, including John O. Brennan, the former CIA director.
At the centre of the case is an expansive theory that attempts to link several investigations involving Trump into what prosecutors describe as a broader conspiracy against him.
Under diGenova’s leadership, prosecutors have spent months examining whether separate investigations — including the probe into alleged links between Russia and Trump’s 2016 presidential campaign and the later investigation into his handling of classified documents — were part of a coordinated effort to undermine his political ambitions.
