Lindsay Clancy is back in court - where will her case go next?

Fundamentally, Clancy's legal team - with Reddington at the helm - is pushing for the charges to be dismissed or dropped. They've explored a variety of legal avenues.

In September, he asked for her to be found not guilty under Rule 25 - a Massachusetts provision that states a defendant should be found not guilty if prosecutors do not present enough evidence at trial.

That request was denied.

Judge Sullivan will hear arguments on several motions on Monday, but Heather Cucolo, a New York Law School professor and mental health law expert, told the BBC that the hearing will likely focus on a narrow point: was this an instance of a routine deadlocked-jury mistrial - in which the jury genuinely could not agree - or was this an improperly terminated trial?

She said Reddington may argue that a retrial could violate Clancy's Constitutional protection against double jeopardy - a legal standard that says a person cannot be tried for the same crime twice.

But legal experts agree that outcome is unlikely.

"The public attention that's been put on this trial and the need to have some conclusion in the near future, I think that the judge is going to say that this mistrial was appropriate, was legally accurate, and that they need to now look to set a date for a retrial," Cucolo said.

Judge Sullivan could make a determination over whether the case can proceed on Monday or he could rule later in writing, criminal defence lawyer Elyse Hershon told the BBC.

And how the District Attorney's office wants to proceed could be determined ahead of Monday's hearing, during it or even days after, she said.

"The three charges of first-degree murder are still pending; they are still hanging over Lindsay Clancy's head unless and until the DA announces otherwise," Hershon said.

Historically, Cruz, the district attorney, has made comments and announcements about the case at press conferences after court finishes. That could happen again this week, she predicted.

It is also likely, Hershon said, that Judge Sullivan pushes the lawyers on both sides to get a trial date on the calendar during Monday's hearing.

"It does not mean it's definitely going to be a jury trial, but [they will want to] put something in the books, hold those dates. It's a big chunk of time. It's four, five, six weeks of the court calendar; that's hard to fit in at the last minute," she said.

"I would anticipate they block off the time while they go through all these motions and the DA's office figures out what it wants to do."