The conspicuous lack of charges against Michael Flynn and Michael G. Flynn, despite reports that Robert Mueller already has enough evidence to arrest the former national security adviser and his son, invites the obvious question: has the elder Flynn already turned state’s witness? The tantalizing possibility that Flynn, like George Papadopoulos, has flipped, gained new currency last week when The New York Times reported that Flynn’s lawyer, Robert Kelner, had ended an agreement to share relevant information about the ongoing Justice Department investigation with Donald Trump’s legal team—a move that could presage a new arrangement with Mueller. Jay Sekulow, an attorney for Trump, dismissed that interpretation at the time, telling the Washington Post, “No one should draw the conclusion that this means anything about General Flynn cooperating against the president.” But a new report that Kelner met with members of the special counsel’s team suggests that Flynn has, in fact, cut some kind of deal.

According to ABC News, Kelner visited Mueller’s offices in Washington, D.C., on Monday—a development that could indicate the two sides are discussing a plea deal. (Keller declined to comment on the meaning of the meeting.) That could have far-reaching implications for the president and members of his campaign. Of the many Trumpworld characters ensnared in Mueller’s probe, Flynn is perhaps one of the most pivotal; not only does he lay claim to some of the most questionable Russian contacts, but he could also prove to be immeasurably valuable in revealing whether the Trump campaign colluded with the Kremlin to derail Hillary Clinton’s candidacy. If anyone knows where the bodies are buried, it’s the man who acted as a key adviser to Trump during his insurgent bid for the White House, the transition, and the early, tumultuous days of his presidency.

Flynn’s testimony could also prove critical in the matter of former F.B.I. director James Comey, whom Trump fired after Comey declined to curtail his investigation into Flynn. (Comey’s dismissal, by Trump’s own admission, was prompted by the Russia investigation, though how exactly that relates to Comey’s interest in Flynn remains to be seen.) An obstruction of justice case “requires a corrupt motive, a corrupt intent,” as Kendall Coffey, who was a Florida U.S. attorney during the Clinton administration, recently told told my colleague Chris Smith. “How much did Trump know about Flynn’s conduct? What were their conversations? Did Trump tell Flynn that he was getting a lot of help from the Russian government?”

What Flynn is willing to say likely depends on what Mueller already knows. It has already been reported that Flynn belatedly registered as a foreign agent for more than $500,000 worth of lobbying work he did on behalf of the Turkish government; he is also being scrutinized for his appearance at a gala for a state-owned Russian media outlet, for which he was paid $33,000; his failure to disclose a trip to the Middle East as part of a broader plan to build nuclear plants in the region; and for his alleged role in a bizarre plot to kidnap Muslim cleric Fethullah Gulen, which his lawyer has denied. “There appear to be potentially indictable cases with respect to Flynn’s security forms,” Coffey added. “But if Flynn was negotiating with the Turkish government to assist in the removal of a political opponent, that couldn’t be ignored by Mueller, and it’s the kind of thing that can’t be thoroughly examined quickly.”