(CNN) A criminal appellate prosecutor who was part of an ongoing subpoena fight related to the special counsel's investigation into Russian election interference concluded his detail with the team in December, the special counsel's office has announced.

The announced departure of Scott Meisler comes amid growing indications the special counsel is winding down the investigation.

Of the 17 prosecutors who joined Mueller's team within the Justice Department since May 2017, Meisler is the fourth known to have to exited the office.

He is still working for the Justice Department and on cases related to Robert Mueller's investigation, according to Peter Carr, a spokesman for the unit run by Mueller. Other divisions of the Justice Department have taken on more responsibility in matters launched by Mueller.

"Scott Meisler concluded his detail with the Special Counsel's Office in December 2018 and returned to the Criminal Division but continues to represent the office on specific pending matters that were assigned to him during his detail," Carr said on Tuesday.

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