Mueller’s longtime aide Aaron Zebley will appear alongside him for House Judiciary testimony

Robert Mueller will bring along one of his deputies to his testimony before the House Judiciary Committee on Wednesday: his longtime aide, Aaron Zebley.

Zebley will sit beside Mueller at the hearing, but he won’t officially be a witness testifying, and will instead be available as counsel to advise Mueller on answering questions, according to the New York Times’s Nicholas Fandos.

Zebley worked closely alongside Mueller during the nearly two-year special counsel investigation. Before that, Zebley had been Mueller’s chief of staff when he was FBI director, and had then worked with him at the law firm WilmerHale.

Mueller had reportedly initially made a late request that Zebley be sworn in as a witness during at least one of his congressional hearings. That would have permitted Zebley — rather than Mueller — to answer some of the lawmakers’ questions.

But Republicans protested this, with Rep. Doug Collins (R-GA) arguing that Zebley’s late addition could jeopardize House rules.

“If true, the chairman’s unprecedented decision to allow a witness’s counsel to both advise him privately and simultaneously testify alongside him shows the lengths Democrats will go to protect a one-sided narrative from a thorough examination by committee Republicans,” Collins said in a statement.

So this proposal was scrapped, and now Zebley will just be there advising Mueller, rather than testifying himself.

Mueller spokesperson, however, said that the committees had been notified of Zebley’s appearance with ample notice.

“Aaron Zebley was the deputy special counsel and had day-to-day oversight of the investigations conducted by the Office,” the statement read. “He will accompany special counsel Mueller to the Wednesday hearings, as was discussed with the committees more than week ago.”

Who is Aaron Zebley?

As Vox’s Alex Ward previously reported, Zebley is a former federal prosecutor and special agent in the FBI’s counterterrorism division for seven years and also served as chief of staff during some of Mueller’s time as FBI director. He’s been involved in some top terrorism cases, including tracking down the al-Qaeda terrorist responsible for the 1998 US Embassy bombings in East Africa.

After Mueller left the FBI to work at the law firm WilmerHale, Zebley joined the firm as well. He then accompanied Mueller back into government once he was appointed special counsel in 2017.

There, Zebley was intimately involved in the special counsel investigation, including overseeing personnel and often serving as the go-between between Mueller’s team and the Department of Justice.

Democrats had already wanted to question Zebley, along with another special counsel prosecutor, James Quarles, in closed-door testimony following Mueller’s public hearing. The Justice Department resisted that idea, and according to CNN’s Shimon Prokupecz, that hasn’t changed.

Mueller’s testimony has already faced plenty of hurdles, from his own reluctance to appear to a one-week delay. Zebley’s appearance adds yet another twist.