Retired FBI agent James Gagliano, who has worked under both former FBI Director James Comey and Special Counsel Robert Mueller, who also once helmed the bureau, said he's "troubled" by the relationship between the two men.

Ever since Mueller was appointed to oversee the Russia investigation in mid-May, just days after Comey leaked memos of his private conversations with President Donald Trump, Gagliano has had reservations, he told CNN host Poppy Harlow.

“The only thing that has troubled me from the start [is] … why would you appoint a special prosecutor that has a personal relationship with one of the central figures in the investigation,” Gagliano said Monday morning of Mueller and Comey, both of whom he “respects.”

Harlow asked the ex-FBI agent to explain his concerns.

“My criticism is the special prosecutor, Robert Mueller, has a personal relationship with former Director Comey,” he reiterated. “Why would you appoint a special prosecutor to conduct an investigation where a central witness and figure has a personal relationship?”

The CNN anchor turned to network legal analyst Paul Callan, who agreed that Mueller was an “odd choice” to oversee the Russia investigation.

“I think to put [Mueller] in charge of the investigation now of Comey — that, maybe, could be problematic,” he explained.

Ex-FBI agent James Gagliano raises concern about Special Counsel Mueller having "a personal relationship" with Comey https://t.co/0YVUGtiLxG — CNN Newsroom (@CNNnewsroom) June 12, 2017

Gagliano’s comments came just days after Comey admitted to the Senate Intelligence Committee that he leaked to “a close friend” memos of his conversations with the president shortly after being fired as FBI director.

“I asked a friend of mine to share the content of the memo with a reporter,” Comey said. “I didn’t do it myself for a variety of reasons, but I asked him to, because I thought that might prompt the appointment of a special counsel.”

The New York Times first reported on the leaked memo on May 16. Less than two days later, Comey got his wish: Mueller was appointed special counsel for the ongoing Russia investigation.