What does this mean? Perhaps nothing more than Cy Vance wanting to enjoy life after more than a decade as Manhattan DA. The news of Vance’s retirement comes at a curious moment, as his office conducts perhaps its most politically explosive investigation ever — and after its most notable Supreme Court victory:

Cy Vance announced Friday he would not seek another term as Manhattan District Attorney, a position he used to prosecute Harvey Weinstein and investigate former President Donald Trump.

Vance is departing this December after more than a decade atop one of the most prominent and powerful prosecutors’ offices in the country. It is expected he will either charge a crime or close the investigation of Trump before he leaves office.

Vance sent Weinstein to prison for 23 years in a case that gripped the nation for months. That would be small potatoes against any trial of Donald Trump. The outcome of such a prosecution would impact national politics on multiple levels and potentially upend political parties as a result. And as NBC News points out, it’s not just the Trump case that’s incomplete:

He recently obtained Trump’s tax returns and underlying documents from the former president’s accounting firm Mazars USA after the Supreme Court declined to stop their production. Vance has been seeking tax returns covering eight years for a grand jury investigation of hush money payments and other financial transactions.

Vance is also investigating former Trump senior adviser Steve Bannon in connection with his role in a charity that was supposed to use private funds to build the southern border wall.

Bannon would be an appetizer, relatively speaking, although still a high-profile target. Trump is the main battle, a battle that would potentially stake out a national first — a former president with ambitions to return to the office being tried for felonies that would disqualify him. The closest we have ever come to that was Travis County’s politically motivated attempt to derail Rick Perry’s presidential bid with a bogus indictment over a veto, but a Trump prosecution would be both more substantial and far more spectacular in impact.

What makes this decision intriguing is that any indictment of Trump would likely take months if not years to bring to trial, given the near-limitless legal resources of both sides. Would Vance pursue an indictment, only to leave the trial to a successor? Why not run for one more term if an indictment was likely?

A profile of Vance by Jane Mayer in the New Yorker today doesn’t entirely answer that question. Vance tells Mayer that he’d already decided to retire before the Supreme Court decision, but he delayed disclosing his intentions to protect his case against Trump on tax records. That raises even more questions, though:

He had decided to keep his intentions quiet until after the Supreme Court ruled on Trump’s tax records, partly because he feared that some of the more outspokenly anti-Trump candidates for his job might alienate the conservative Justices. His decision to leave midcourse, however, exposes the case to the political fray of an election. Some candidates have already made inflammatory statements denouncing Trump, and such rhetoric could complicate a prosecution.

The investigative phase of the Trump case will likely be complete before Vance’s term ends, leaving to him the crucial decision of whether to bring criminal charges. But any trial would almost surely rest in the hands of his successor. Daniel R. Alonso, Vance’s former top deputy, who is now a lawyer at Buckley, L.L.P., predicts that if Trump is indicted “it will be nuclear war.”

Don’t the same concerns about “rhetoric” apply to a trial record, just as they might in a Supreme Court appeal? One strategy for Trump’s team will be to argue, especially on appeal, that the entire prosecution was politically motivated. Vance may be “famously low-key,” as Mayer writes, but his successor almost certainly won’t be. And the Supreme Court may not have been sympathetic to Trump’s complaints about politicization in the fight with Vance, but they were sympathetic about those complaints in the parallel fight with the House over the same records.

So here’s my question: would a DA who has spent years trying to get Trump’s records to build a criminal case against him decide to retire — and risk seeing all of that work go to naught under someone else’s management? Or even more simply, why go through all Vance did just to walk away from it if he can get an indictment and conviction by running for one more term? It’s possible, but it certainly seems odd.

Mayer insists that her sources tell her it’s full speed ahead, and thinks that Vance’s most recent addition to the team is meant to bridge that gap:

Several knowledgeable sources told me that, in the past two months, the tone and the pace of Vance’s grand-jury probe have picked up dramatically. A person who has been extensively involved in the investigation said, “It’s night and day.” Another source, who complained that things had seemed to stall while Vance waited for Trump to leave the White House, and then waited for his tax records, said, of the D.A.’s office, “They mean business now.” Earlier, this source had felt that Vance’s team seemed slow to talk to some prospective witnesses. But recently, the person said, prosecutors’ questions have become “very pointed—they’re sharpshooting now, laser-beaming.” The source added, “It hit me—they’re closer.”

The change came soon after the D.A.’s office made the unusual decision to hire a new special assistant from outside its ranks—Mark Pomerantz, a prominent former federal prosecutor. Pomerantz was brought on, one well-informed source admits, partly “to scare the shit out of people.” The press has characterized Pomerantz, who formerly headed the criminal division of the U.S. Attorney’s Office for the Southern District of New York, as a specialist in prosecuting organized crime, largely because he supervised the team that, in 1999, obtained a conviction of the son of John Gotti, the don of the Gambino crime family. In fact, it was not a major case. Pomerantz’s deeper value, say those who know him, is that he has spent the past two decades at the eminent firm Paul, Weiss, artfully representing rich and powerful white-collar criminal defendants. This experience makes him capable not just of bringing a smart case but also of anticipating holes through which a wily target might escape. “He’s a brilliant lawyer,” Roberta Kaplan, a litigator who has worked with Pomerantz, said. “He knows when to push and when not to.” Anne Milgram, a former attorney general of New Jersey, who previously worked in the Manhattan D.A.’s office, under Morgenthau, said that Pomerantz “likely has greater stature than any of the candidates for D.A. right now.” She believes his presence will insure that the Trump case is in steady hands when Vance’s successor takes office. Given Trump’s talk of a witch hunt, Milgram noted, the fact that Pomerantz comes from outside the D.A.’s office helps take the case “out of politics.”

Well, maybe. But it still doesn’t answer the question as to why Vance would leave with all of this still in the air, especially since winning re-election would appear to be a slam dunk. Walking away now at least gives the appearance that Vance thinks there’s not much to walk away from.