Just how far back will Robert Mueller reach to make a determination about alleged collusion with Russians in the 2016 election cycle? A series of subpoenas issued last month puts the date at November 2015, a point where a grand jury has compelled a number of witnesses to surrender communications related to Donald Trump and nine other campaign figures. NBC News and Axios reported on the story last night, but there’s not a lot of context for the subpoenas in their analyses:

The grand jury investigating alleged collusion between Russia and Donald Trump’s presidential campaign has issued a subpoena seeking all documents involving the president and a host of his closest advisers, according to a copy of the subpoena reviewed by NBC News.

According to the subpoena, which was sent to a witness by special counsel Robert Mueller, investigators want emails, text messages, work papers, telephone logs and other documents going back to Nov. 1, 2015, 4½ months after Trump launched his campaign.

However, the subpoenas are not aimed at Trump himself or the White House. Instead, the demand for documents has been made on other witnesses, who will have to release their communications with or about ten people. Trump’s on that list, as are Paul Manafort and Rick Gates, both of whom got indicted for crimes entirely unrelated to campaign issues. Some of the other names reflect obvious interest, such as Steve Bannon, Carter Page, and Roger Stone. Others seem like a reach, such as former bodyguard Keith Schiller and now-departing comms director Hope Hicks.

One in particular might pose some potential issues for both Trump and Mueller — Michael Cohen, Trump’s lawyer, whose advice to Trump would normally be covered by attorney-client privilege. That’s not true of his communication with other figures in the case, however, to whom these subpoenas have been issued. Did the odd arrangement with Stormy Daniels, in which Cohen claims to have paid her $130,000 out of his own pocket over an alleged affair with Trump, trigger more than curiosity in the special counsel office? Or was he already on Mueller’s radar? Probably a little of both.

However, there are a couple of notable names missing here, too. Both Michael Flynn and George Papadopoulos have had to take plea deals in Mueller’s probe and supposedly are cooperating on the collusion probe, but neither NBC nor Axios report that they’re among the subjects for subpoenaed documentation. Does that suggest that they’re dry holes in the collusion probe? For that matter, where are names like Donald Trump Jr and Jared Kushner, who are also supposedly linchpins of this theory?

Axios’ Jonathan Swan, who also reported on the story, implies that this may be a shotgun approach for investigators who have not been able to make a case yet. It also means that this is going to drag out for a while as witnesses turn over documents:

In December, the president’s lawyer Ty Cobb told me the White House would be free of the Mueller investigation “shortly after the first of the year absent some unforeseen delay.”

We know very little about what’s keeping the investigators so busy, but the breadth of this subpoena means Mueller’s team could easily stumble into goodies about Trump’s inner circle given so many people are coughing up material. (Cobb didn’t respond to a request for comment.)

Investigators have already conducted interviews with significant potential witnesses, so this could be a chance to see if any of them can be impeached and then flipped. Alternatively, it may also mean that Mueller and his team are wrapping things up and want to make sure they have everything relevant to the investigation before reaching conclusions. The missing names off this list make it seem more like the latter than the former, especially since no evidence has yet emerged that there was any collusion with Russians, and since the inner-circle figures assumed to be involved in such theoretical connections aren’t named on this list.