A ‘mystery’ Mueller grand jury witness is set to appear before a DC court in just two weeks

The D.C. Circuit Court of Appeals on Friday announced that it will hear an appeal by a "mystery" witness for special counsel Robert Mueller's grand jury behind closed doors.

As reported by Politico's Josh Gerstein, the D.C. Circuit is scheduled to hear out the unidentified witness on December 14 in a closed-door session.

Politico reported last month that an identified grand jury witness has been resisting giving up information as part of the Mueller probe into Russian interference in the 2016 presidential election.

So far, there has been no indication of who this witness is or what information they may have. Additionally, the docket in the case was so bereft of details that Politico had difficulty at first in even determining whether it was related to the Mueller probe at all.

"This can get a step or two weirder than it already is," a lawyer representing a senior Trump staffer told Politico at the time. "It could be anyone who’s been subpoenaed by the special counsel for anything."