A Massachusetts judge has declared a mistrial in the murder trial of Lindsay Clancy after jurors were unable to reach a unanimous verdict on whether she should be held criminally liable for the deaths of her three young children.

The decision from Judge Sullivan brings an abrupt halt to the six-week court proceedings, with the jury deliberating for more than 40 hours over seven days before conceding they were permanently deadlocked.

"At this point, I'm going to declare that the jury is deadlocked, and I'm going to declare a mistrial," Judge Sullivan told the court on Friday, formally dismissing the panel after they signalled their deadlock for a third time.

To understand the background to this case, the 36-year-old former nurse was facing three counts of first-degree murder over the strangulation of her children — five-year-old Cora, three-year-old Dawson, and eight-month-old Callan — at their Massachusetts home in 2023.

Clancy does not deny killing the children, but entered a plea of not guilty. Her defence lawyers argued that she was suffering from postpartum psychosis at the time and should not be held criminally responsible. After the killings, Clancy cut herself with a knife and jumped from a second-storey window in an attempted suicide that left her paralysed.

Under US law, a conviction requires jurors to unanimously agree that the accused is guilty beyond a reasonable doubt, placing the burden entirely on the prosecution. A hung jury does not mean Clancy has been found not guilty, nor does it mean prosecutors proved their case; it simply leaves the legal proceedings without a final verdict.

The final hours in court involved significant legal arguments from the defence. On Friday morning, Clancy's lawyer, Kevin Reddington, pushed for a member of the jury to be removed after a note sent the previous day indicated one juror was not following instructions regarding reasonable doubt.

Judge Sullivan denied that request and sent the panel back to continue their discussions. Roughly an hour later, the jurors returned to confirm they still could not agree, prompting the judge to conclude he had no choice but to end the trial.

Reddington made an immediate emergency appeal to the Massachusetts Supreme Judicial Court, asking the state's highest court to force continued deliberations and order the judge to question the panel about the holdout juror. That request was rejected, allowing the mistrial declaration to stand.

Clancy appeared downcast and expressionless as the ruling was confirmed in a silent courtroom. Her defence counsel indicated he intends to file a further motion requesting that the mistrial decision be reconsidered.

What we do not know yet is whether the state will pursue a second trial. Plymouth County District Attorney Timothy Cruz said he would meet with his legal team before deciding how to proceed, confirming: "There will be no decisions made today."

Prosecutors now have several options available, including seeking a retrial or attempting to reach a plea agreement. A hearing has been scheduled for 29 September, where prosecutors may outline their next steps. Until then, Clancy will remain held on the murder charges at the mental health facility where she is currently housed. I'll be following this one — check back for updates.