NBC News: Mueller's First Russia Indictment Will Be Served Monday

The first indictment from Special Counsel Robert Mueller's probe into Russian interference in the 2016 presidential election will be served on Monday, even though what charges are included and who will be served remains unknown, a source told NBC News on Saturday.

The network, quoting an unnamed U.S. official with firsthand knowledge of the case, confirmed the news, and NBC reported the news with a second source.

CNN was the first to report on Friday citing several sources, that the grand jury had approved initial charges, and that the charges are remaining sealed at this time through a federal judge's order.

Saturday afternoon CNN reported that there could be "more than one person," and that the indictments themselves were handed up on Friday and that charges were filed.

If someone is taken into custody or surrenders on Monday, that person would go before a judge in Washington D.C. to hear the charges, beginning the legal process.

"So far from all the attorneys that we've talked to who are associated with some of the people who are being investigated have either not called us back, and the few that we have talked to have said their clients have not been asked to surrender yet," said CNN crime and justice reporter Shimon Prokupecz. "They have not been told if their clients are the ones that are facing the charges. All that is still a mystery. Right now it appears that Monday will be the big day. All of this is subject to change depending on what the special counsel decides to do."

Keeping indictments sealed "is fairly common at the stage when you have an indictment that is issued or approved, as it may have been today," former U.S. Attorney Barbara McQuade told MSNBC Friday.

"The reason is that law enforcement kind of wants its ducks in a row before they go out and arrest the defendant or even notify him," said McQuade. "It may be that they don’t arrest whoever this defendant is because they've worked out a relationship with his or her defense attorney to bring them in to appear on the case."

Already, President Donald Trump's former campaign manager Paul Manafort and retired Lt. Gen. Michael Flynn, the president's first national security adviser, have long been central in Mueller's investigation, but neither man's representatives have responded for requests for comment.

The news came one day after White House Press Secretary Sarah Sanders told Fox News the White House believes the Mueller investigation is coming to an end.

She based her comment on reports concerning payments that the campaign team for Democratic nominee Hillary Clinton and the Democratic National Committee had made toward research for a dossier showing Trump's contacts with Russians.

The White House has refused comments on the news about the pending indictments. Trump himself has continued to deny that reports of collusion between his campaign and Russia are anything more than a "witch hunt."

CNN reported on Saturday that Deputy Attorney General Rod Rosenstein, who has oversight over the Russian investigation after Attorney General Jeff Sessions recused himself, would have been told of charges before they were presented to the grand jury.

The investigation is looking into whether the Trump campaign colluded with Russia, as well as whether Trump himself obstructed justice by interfering with the case's investigation through his actions, including by firing FBI Director James Comey.

Lobbying efforts done by Manafort, Flynn, and others have come under scrutiny, and Mueller's teams have subpoenaed documents and testimony from many sources, including people close to Manafort.