Predictions for when special counsel Robert Mueller will deliver his much-anticipated report to the attorney general have yo-yoed between days and weeks.

Two things are more definitive: In January, Mueller extended the grand jury for an additional six months, and many pieces of the probe will continue well past its conclusion, be it two weeks or two months from now.

"Certain things can't be wrapped up yet," said Seth Abramson, a former criminal defense attorney who is not involved in the probe and has become popular for his online theories about President Donald Trump and Russia.

There are uncharged crimes, outstanding subpoenas, pending cooperation agreements and unresolved, possibly sealed cases, he said, which would seem to be snipped in the middle if Mueller's report was issued imminently.

But if Mueller is about to shut down the investigation, as a slew of recent reports suggest, the question is why.

Jonathan Meyer, a former Justice Department senior official, said that, if the investigation is in fact ending, one reason is that Mueller may be bending over backward to stay within the scope of his original mandate and make sure the probe doesn't turn into a longer, more wide-ranging investigation.

"He seems laser focused on his assignment, which is to get to the bottom of Russian involvement in the 2016 election," said Meyer, now a partner at Sheppard Mullin. If Mueller's learned everything there is to learn within his mandate, he may feel it's time to wrap up.

What is still outstanding?

Mueller issued a heavily redacted sentencing report on Michael Flynn in December. In it, Mueller outlined the former national security adviser's "substantial assistance" in the Russia investigation and 19 meetings with federal prosecutors.

The memo was not shocking, although it confirmed that the investigation was ongoing. It also revealed that Flynn assisted in a mysterious, unrelated criminal investigation - significant enough that Mueller credited Flynn for his help in a blacked-out portion of the document.

At the time, former federal prosecutor Joyce White Vance said: "Flynn's deal strongly implies there is more to come from Mueller. The memo, with its many redactions, tells us something significant and important is coming, even though we don't know exactly what it is."

We still don't know, Abramson said. No subsequent indictments can be linked to knowledge that in particular Flynn would be privy to.

Up to this point there have also been no charges based on the lengthy cooperation of George Nader, the Lebanese American businessman who acted as an adviser to the United Arab Emirates. Last month, Mueller also re-extended a sentencing hearing for Rick Gates, a top official to Manafort, and told the court that Gates was still assisting the special counsel in several ongoing investigations.

In several cases, additional information could still flow to prosecutors - like the recently indicted Roger Stone, as well as Maria Butina, who pleaded guilty in December, and her boyfriend Paul Erickson, charged earlier this month. Even Trump's former personal attorney, Michael Cohen, and former campaign manager, Paul Manafort, could reveal new information after sentencing.

Abramson also mentioned individuals whom many attorneys anticipated would be charged but have not yet been, including Donald Trump Jr. and Erik Prince, the founder of the former Blackwater contracting firm. He called conservative writer Jerome Corsi the "most obvious example."

Corsi himself expected to be indicted by Mueller's office on charges of lying to investigators. After two months of interviews with the special counsel's office, Corsi told his daily live-stream that Mueller's team said he would be criminally charged.

"I'm going to be indicted. That's what we've been told. Everyone should know that," he said.

If Mueller has met his mandate, what happens next?

Abramson said, "We always assumed Mueller would prosecute any case brought during the investigation himself, but that was a presumption."

Mueller has handed off cases to other prosecutors' offices for months: Washington attorney Gregory Craig and Michael Cohen were sent to the Southern District of New York for federal prosecutors to handle. Cases involving Tony Podesta and Vin Weber were also farmed out.

Former solicitor general Neal Katyal, who drafted the special counsel regulations, said in a New York Times op-ed published Thursday that "a short Mueller report would mark the end of the beginning, not the beginning of the end."

Katyal's theory was that Mueller viewed himself as the chief architect of the investigation phase for a family of cases; he compared them to the internet, "with many different nodes, and some of those nodes possess potentially unlimited jurisdiction."

The report Muller submitted to Attorney General William Barr will detail not each witness's testimony, but Mueller's decision to indict or decline to indict the subjects of the investigation. He could file charges or unseal a large number of indictments at the close of the investigation, then let the Department of Justice prosecute them.

“Their powers and scope go well beyond Mr. Mueller’s circumscribed mandate,” Katyal wrote. “So whenever Mr. Mueller turns in his report, do not assume that things are over.”