Washington (CNN) Rick Gates, a former Trump campaign adviser who faces federal criminal charges in special counsel Robert Muller's investigation, is now facing questions from a federal judge about his arrangement with a Washington lobbyist known for supporting a conspiracy theory on the killing of Democratic National Committee staffer Seth Rich.

Judge Amy Berman Jackson wants Gates to explain why a taped video message to supporters would not violate a gag order placed on lawyers and defendants in the case. Lobbyist Jack Burkman played that video Tuesday night over Facebook Live at a gathering of mostly journalists at a hotel in Northern Virginia that was billed as a fundraiser.

In the video, a bearded Gates thanks donors but shies away from commenting on his case.

Gates must say "why the court should not find that his reported personal participation in the creation of a fundraising video" doesn't violate the gag order, the judge ruled. She also told Gates to detail his relationship to Burkman.

Gates, who was indicted alongside former Trump campaign chairman Paul Manafort, recorded the fundraising video sometime in the last six weeks and pledged he would fight the charges against him. He's pleaded not guilty to eight counts of money laundering and falsifying records.

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