A federal judge has asked for a hearing behind closed doors before she decides whether Paul Manafort lied repeatedly to prosecutors in special counsel Robert S. Mueller III’s investigation into Russian interference in the 2016 U.S. election. The hearing, set for Feb. 4, is just days before the former Trump campaign chairman faces sentencing in Virginia.

If U.S. District Judge Amy Berman Jackson in Washington were to decide he lied and broke his plea agreement, it could mean as much as 10 more years in prison for Manafort when his sentencing is finally set. Manafort faces a possible seven- to 10-year sentence in his related Virginia federal case, according to several legal experts.

The Friday hearing left for another day the merits of the government’s allegation that Manafort “intentionally provided false information” to investigators since pleading guilty in federal court in September.

Prosecutors made clear they will not rule out bringing new charges against Manafort in the future, although they have no plans to do so now.

“I’m not in any way saying it’s our current intention, it’s a plan, it will happen, but want to preserve that ability,” prosecutor Andrew Weissmann said.

Manafort “hypothetically” could be charged with lying to the FBI, with perjury in front of the grand jury or with any of the charges prosecutors dropped in exchange for his plea and cooperation, Weissmann said.

Under Manafort’s plea deal, prosecutors have only to show that their determination he breached the deal was made in “good faith.”

Manafort, 69, dressed in a black suit and red tie, leaned heavily on a cane as he entered court in Washington and did not visibly react to Jackson during the hearing, which the judge called to “nail down” what the “consequences are or will be of the special counsel’s determination” that Manafort breached his plea deal.

Jackson told a courtroom packed with reporters that she knew the decision to seal the February hearing would be unpopular but said prosecutors needed to discuss sensitive matters regarding ongoing investigations and uncharged individuals, and that she did not see how the parties could address those topics in open court without making mistakes.

Jackson said the court would “get as much of the transcript released as possible, as soon as possible.”

“I have not made any decisions yet,” she said, saying she found merit and flaws in arguments from both sides.

Some of prosecutors’ allegations are “confusing or lack context,” she said, while at times the defense rebuttals were “conclusory and short on specifics.”

She said Manafort’s arguments that criminal defendants often misstate the facts in debriefings and correct them later on “have some force.” But, Jackson added, there are other instances in which Manafort “may have lied, pure and simple.”

Manafort pleaded guilty Sept. 14, on the eve of jury selection for the trial in Washington, to conspiring to defraud the United States and obstruct justice, admitting to years of financial crimes related to his undisclosed lobbying work for a pro-Russian political party and Ukrainian politician Viktor Yanukovych. He also was convicted by a jury in August in a separate federal case in Virginia for bank and tax-fraud crimes.

The collapse of Manafort’s cooperation deal revealed that prosecutors knew far more about his activity since his October 2017 indictment than he realized.

Since late November, when Mueller’s office accused Manafort of lying, the special counsel’s office has filed 800 pages of heavily redacted exhibits to provide evidence for their claims that, among other things, Manafort gave contradictory statements in August in a separate Justice Department criminal investigation outside of Washington; falsely denied having ongoing contact with Trump administration officials since they took office in January 2017; and sought to deceive investigators about his interactions with a longtime Russian aide and co-defendant, Konstantin Kilimnik, including by sharing campaign polling data with him in 2016.

The FBI has assessed that Kilimnik, a Russian employee of Manafort’s consulting business, has links to Russian intelligence, prosecutors said in court papers.

In 2017, Kilimnik denied to The Washington Post having connections to Russian intelligence. He is believed to be in Moscow.

Manafort’s attorneys deny he lied, saying he made honest errors and tried to correct them. “Failure of memory is not akin to a false statement,” attorneys Kevin M. Downing, Thomas E. Zehnle and Richard W. Westling wrote in filings to the court.

Jackson of the District of Columbia, had directed both sides to be ready to argue whether Manafort lied as alleged in a 31-page FBI affidavit.

Manafort’s team has argued that “a fair reading” of much of the government’s evidence about the alleged lies “merely demonstrates a lack of consistency in Mr. Manafort’s recollection of certain facts and events,” many of which occurred years ago or during a high-pressure presidential campaign from which he was fired, they noted.

Manafort’s defense has said, and prosecutors agreed, that federal advisory guidelines are expected to recommend that he face the statutory maximum sentence of 10 years in prison under his convictions in the District because of the large dollar amounts involved in his financial crimes.

Still, Jackson said the question of whether he intentionally lied after his plea is a “fundamental issue” she must consider in his sentencing, and “not purely academic.”

Among other things, she could require Manafort serve his District and Virginia sentences consecutively, instead of concurrently. She agreed to Manafort’s request to appear in a business suit, not a prison jumpsuit.

Manafort has been jailed just outside of Washington, in Alexandria, since June, after the witness tampering charge against him and Kilimnik was filed.

Manafort’s defense team inadvertently revealed some of the contested statements about his cooperation agreement in a recent filing when a document formatting error made it possible to view material that was supposed be redacted and blacked out.

Manafort had asked not to have to be present in court Friday, but Jackson declined and said she wanted him there because of the significance of the issues being heard and to be certain he and his defense team were on the same page.

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