Paul ManafortAlex Wong / Getty

Seventeen months, two trials, and one voided plea deal later, the former Trump campaign chairman Paul Manafort has finally learned his fate: He’ll spend about seven years in federal prison for crimes he committed over more than a decade, marking one of the biggest prosecutorial victories for Special Counsel Robert Mueller since he launched his investigation nearly two years ago.

Nevertheless, Mueller might not be quite done with Manafort yet, former prosecutors tell me. Court documents and pre-sentence hearings that dealt with the breach of Manafort’s plea deal suggest that prosecutors might have more ammunition to go after the 69-year-old on matters that go directly to the question of a conspiracy with Russia, rather than the financial crimes and violations of foreign-agent laws that he’s been charged with to date.

Manafort pleaded guilty to tax and bank fraud and failing to register as a foreign agent for Ukraine. But he “intentionally made multiple false statements” to the FBI, the special counsel’s office, and the grand jury “concerning matters that were material to the investigation: his interactions and communications” with the suspected Russian intelligence officer Konstantin Kilimnik, D.C. District Court Judge Amy Berman Jackson ruled last month. As such, questions remain about Manafort’s interactions with Russians during the campaign—questions that go to the main focus of the Mueller investigation into a potential election conspiracy.

“The ‘no collusion’ mantra is simply a non sequitur,” Jackson said during Manafort’s sentencing hearing on Wednesday, referring to Manafort’s attorneys’ claim that Mueller had found no evidence of collusion with Russia. “It’s also not accurate because the investigation is ongoing.”

The first clue that Mueller’s interest in Manafort goes beyond his financial crimes came early last month, when one of the top prosecutors on Mueller’s team, Andrew Weissmann, said in a closed-door hearing that a meeting Manafort had in August 2016 goes “very much to the heart of what the special counsel’s office is investigating.” (Manafort’s deputy Rick Gates was also at the meeting, The Washington Post said, citing court records. A status update for Gates, who has been cooperating with Mueller, is due on Friday.) During that meeting Manafort provided internal Trump-campaign polling data to Kilimnik and discussed a “Ukraine peace plan” favorable to Russia. Mueller was appointed in May 2017 to investigate “any links and/or coordination between the Russian government and individuals associated with” Trump’s campaign, as his appointment memo described it; Jackson agreed that the topic of Manafort’s meeting was at “the undisputed core of the Office of Special Counsel’s investigation.”

But Weissmann’s tantalizing comment wasn’t resolved in the government’s sentencing memo for Manafort; on the contrary, details about the August 2016 meeting were conspicuously absent from the 800-page document. The episode was briefly brought up in Manafort’s sentencing hearing on Wednesday, when Jackson reaffirmed that Manafort had lied to the government about the meeting in his conversations with Mueller’s team. “I still find that the special counsel’s office proved that Manafort intentionally gave false testimony with respect to that matter,” she said. And it was only one of “several matters he lied about with regard to Mr. Kilimnik,” she added.

The topics discussed during the August 2 meeting might be the closest thing to a “smoking gun” of collusion that has been revealed so far. A footnote in a court filing submitted by Manafort’s attorneys last month, first noticed by the national-security journalist Marcy Wheeler, indicates that Manafort and his deputy sent 75 pages of polling to Kilimnik and that Kilimnik sent at least six emails to the pair discussing the data. Richard Westling, Manafort’s lawyer, denied that Manafort had lied about the content of the August 2 meeting and said that while the data that Manafort shared with Kilimnik was “very detailed” and “relevant” to a meeting the campaign had had earlier in the day, it would not have been useful to the suspected Russian spy. "It frankly, to me, is gibberish,” Westling said. “It’s not easily understandable." Jackson shot back: "That’s what makes it significant and unusual.”

Still, the content of the 2016 meeting was only revealed by accident due to a redaction error by Manafort’s lawyers, and the significance of the episode to Mueller’s main probe, while hinted at by Weissmann, has yet to be fully explained.

“It’s hard to imagine that something so explosive and central to the mission of his investigation wouldn’t be addressed either in charges against someone (Manafort or others) or in a report,” Mimi Rocah, a former federal prosecutor in the Southern District of New York, wrote in an email. “And the fact that the special counsel hasn’t brought it out but it was only revealed inadvertently, reinforces the idea that [Mueller] is saving it for something else.”

That “something else” could be anything from a line in Mueller’s report to an entire conspiracy charge. “My money is on Mueller including the Manafort efforts as part of the ‘case’ alleging Trump campaign collaboration with the Russians,” Patrick Cotter, a former federal prosecutor who specialized in organized crime, told me in an email. “The question then is, what is the best way to make that case? For myself, I believe a RICO [Racketeer Influenced and Corrupt Organizations Act] indictment would be the appropriate vehicle to bring such a case: charge the campaign as the ‘racketeering enterprise’ and name Trump, Manafort and the rest of the gang as members of the enterprise … straight out of the mob prosecution playbook.”

Cotter, who is familiar with Mueller’s by-the-book style but has no direct knowledge of his internal plans, said Mueller is more likely to take the “safer route”—laying out all the facts that would support such a case in a report, “but not actually charging the legally plausible but politically nuclear formal criminal case.” Any RICO indictment against the campaign for a conspiracy with Russia “would be the new definition of bold and cutting edge.” The former federal prosecutor Jeffrey Cramer agreed that Mueller could bring a conspiracy case and name Manafort and others as unindicted co-conspirators—but if the evidence doesn’t rise to the level of proof beyond a reasonable doubt, it will likely just be outlined in the report.

A spokesman for the special counsel’s office declined to comment. A lawyer for Manafort didn’t return a request for comment.

Whatever path Mueller decides to take, there is no shortage of lingering questions about Manafort’s role in a potential conspiracy. “This hasn’t been resolved at all,” Representative Adam Schiff, the Democratic chairman of the House Intelligence Committee, told me on Thursday. “What Manafort chose to do was to conceal evidence of collusion from the special counsel’s office and from the court, and then have his lawyer go out on the courthouse steps and say there was no collusion.”

Schiff suggested, moreover, that Mueller knows a lot more about Manafort than his office has so far let on. “We have not had access to Manafort and I don’t know whether we ever will,” he said. “But the special counsel’s office does have information about this.” Schiff added that the lingering questions about Manafort’s role underscore how important it is that Mueller’s final report be provided to Congress—and that the report include all of the underlying evidence Mueller collected, regardless of whether it results in a conspiracy charge. “Our standard is not whether there is proof beyond a reasonable doubt,” Schiff said, “but whether there is a risk to national security.”

Regardless of Mueller’s next steps, Manafort is set to spend at least six years in federal prison. Kevin Downing, Manafort’s other lawyer, appeared to be playing for a presidential pardon when he told reporters on the courthouse steps on Wednesday that no evidence of Russian collusion had been found. But a pardon might now prove useless—Manafort now faces state charges in New York, where the Manhattan District Attorney’s Office charged him on Wednesday in connection with a multimillion-dollar mortgage-fraud scheme.

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