If Manafort were in a position to definitively answer that question, it seems unlikely he would have accepted this plea agreement. He would have been in a position to hold out for something far better.
As part of the plea, he agreed to coöperate with the special counsel, Robert Mueller. Manafort will lose several properties, the money in several bank accounts, and a life-insurance policy, which appear to have value well in excess of ten million dollars. In exchange, Manafort was assured that he will spend no more than a decade in prison for the two charges, so long as he fully coöperates with Mueller.
.. The plea agreement specifically requires Manafort to disclose to the government “his participation in and knowledge of all criminal activities.”
.. But, even if Manafort had very little helpful to offer, he said, “this is a good deal for Mueller.” Mueller gets another guilty plea and avoids a potential loss at trial, which serves to undercut Trump’s repeated argument that the Mueller investigation is a “witch hunt.” Even if Mueller already knows everything that Manafort has to offer, it would be helpful to have another voice confirming details at some future criminal trial for some other defendant.
.. Among the Trump team, Manafort would be, by far, the most experienced in dealing with emissaries from Russia and its allies, and the one most likely to understand the various agendas of those present. He surely knows what he told Trump, Jr., Trump himself, Kushner, and others about the significance of the meeting.
.. Manafort can also potentially shed light on several key people and a number of events that the public still knows too little about. Was Manafort’s employee Konstantin Kilimnik a Russian intelligence asset? And did he serve as a channel between the Trump campaign and Moscow? When Manafort pondered giving Oleg Deripaska—a Russian oligarch close to Putin—insider access to the Trump campaign, what did he mean? What, if anything, did he end up offering Deripaska?
.. Rather than merely informing on others, this theory holds that he would be able to lay out the full story of collusion (if, indeed, there was any).
.. However, this plea agreement is not overly generous. It strips Manafort of much of his wealth and means that the man, who is sixty-nine years old, will likely spend a decade in prison.
.. This could be because Manafort doesn’t know as much as we might imagine, or, more likely, that Mueller already knows most of what Manafort could tell him.
.. the Mueller investigation will likely come down to one central question: Did senior members of the Trump campaign, with the explicit knowledge of Trump himself, actively work with Russian government actors to help sway the election so that Trump would win? If the answer is yes, then Trump will almost certainly be impeached and removed from office.