Barry Pollack, WikiLeaks founder Julian Assange's Washington, D.C.-based attorney, has left Miller & Chevalier for a smaller boutique law firm and is representing an unnamed client involved in special counsel Robert Mueller's Russia probe.

“I am representing someone with respect to the Mueller probe,” said Pollack, who is now a partner at Robbins, Russell, Englert, Orseck, Untereiner & Sauber. “The representation is not public at this point,” he said.

Pollack said Assange, whose organization in 2016 released troves of Democratic Party emails stolen by Russian hackers, has not been contacted by Mueller's office thus far. Pollack said he is representing Assange only in relation to an ongoing criminal investigation in the Eastern District of Virginia. He gave no hints as to who he was representing in connection with Mueller's investigation.

Last month rumor spread that former Trump campaign official Richard Gates had retained Pollack, following a report in The Daily Beast. Pollack told The National Law Journal he did talk to Gates about representing him at trial, before Gates ultimately pleaded guilty, but he was never retained.

“I had spoken to Mr. Gates about the possibility of representing him at trial if he was not able to resolve the case through a plea,” Pollack said. “Obviously, ultimately he decided that he did want to resolve the case through a guilty plea, and so there was no need for me as trial counsel. When I had spoken with him it was about the potential of representing him at trial, if [Sidley Austin senior counsel] Tom Green was not able to get a plea deal for him that he thought was in his best interest to take.”

Pollack added, “I have not spoken with anybody else [besides Gates] who has been charged or is in a position where they're looking for trial counsel with respect to that investigation.”

The timing of Pollack's exit from Miller & Chevalier follows a familiar path for attorneys with clients in Mueller's crosshairs. Kevin Downing, a defense lawyer for former Trump campaign chairman Paul Manafort, left Miller & Chevalier last year, with the firm citing a client conflict. Downing has continued to represent Manafort, who has pleaded not guilty to criminal charges.

Pollack gave no indication that he was also leaving Miller & Chevalier because of conflict issues. He said he wanted to join Robbins Russell because he thinks his practice brings trial-level criminal work that is a better fit for the firm. Pollack said Miller & Chevalier had a number of practice areas that were not necessary to support his work.

“I had been at Miller Chevalier for a little over nine years, and it is an excellent firm, but it has grown,” Pollack said. “Robbins Russell is more of a litigation boutique: A little bit smaller and just a very high-end litigation firm, and a firm that I feel like I can really be part of the next generation at that firm and that's an exciting opportunity.”

Robbins Russell counts 35 attorneys on its website, including Pollack, while Miller & Chevalier has little more than 100 lawyers in its ranks.

Pollack also said he will continue to represent Assange while working as partner at Robbins Russell, but he will do so though his own independent firm, not through his new firm. Pollack said Robbins Russell did not want to take on Assange's representation “for a variety of client and other reasons,” but he said the firm also did not want to interfere with Pollack's relationship with Assange.

Pollack said his independent representation of Assange is unique to the controversial WikiLeaks founder.

“There are not presently other clients that fall in that same category [as Assange], but part of the idea of establishing my own firm is that if there are representations that I want to take on that for whatever reason Robbins Russell does not, it would give me the flexibility to do that,” Pollack said.