A United States (US) judge declared a mistrial in the murder trial of Lindsay Clancy after a jury failed to reach a unanimous verdict over whether she was criminally responsible for killing her three children in 2023.

Judge William Sullivan declared the mistrial on Friday after jurors deliberated for roughly 38 hours and repeatedly told the court they could not reach a consensus.

The jury, comprising nine women and three men, had twice informed the judge earlier in the week that it remained deadlocked. On Friday, the jury returned to court and said, “with a heavy heart” that it could not “and will not be able to” reach a unanimous decision.

The jury was split 11-1, although the direction of the split was not disclosed by the court.

Clancy’s defence lawyer Kevin Reddington had sought the removal of the juror who he said prevented the remaining 11 jurors from reaching a not-guilty verdict.

Reddington later described the mistrial as a victory for the defence and blamed the outcome on the holdout juror.

“They know that they were robbed, by one man, for whatever his agenda was, who stole seven weeks of the lives of these other jurors,” Reddington said.

He also said that he had “won” the case and “crushed” the prosecution’s arguments. Reddington described Clancy as a “brave” and “wonderful” person whose life was “a tragedy” and said that she would be ready for another trial if prosecutors decided to pursue one.

Plymouth County district attorney Tim Cruz said that his office had not decided whether to seek a retrial. Speaking outside the courthouse, Cruz said that the case was “not about the healthcare system or how women are treated in it.”

“The case was and has always been about getting justice for those three little babies. We’re here at this courthouse today because those children are not,” he pointed out.

Clancy, 36, faced trial over the deaths of her three children, Cora, 5, Dawson, 3, and eight-month-old Callan, in January 2023 at the family home in Duxbury, Massachusetts.

No one disputed that Clancy strangled the children with exercise bands. After the killings, she cut herself with a knife and jumped from a second-storey window in an attempt to take her own life, leaving her paralysed.

Her defence argued that she killed the children while suffering from severe postpartum psychosis and should be found not guilty by reason of insanity.

Prosecutors argued that Clancy understood the wrongfulness of her actions and intentionally killed her children. They presented testimony from a psychologist who examined Clancy and concluded that she had planned to take her own life and killed the children because “she was convinced that they would suffer without her”.

Prosecutors also pointed to evidence showing that Clancy sent her husband to collect a food order and visit a pharmacy after using her phone to calculate how long he would be away.

Testimony from Clancy’s former husband Patrick Clancy focused on her mental health problems in the months after the birth of their third child. He said that she repeatedly sought treatment from healthcare providers, who prescribed her several medications.

Patrick testified that Lindsay had left a psychiatric hospital weeks before the killings but showed no indication in the days before the incident that she planned to harm herself or their children.

He said that she appeared to have a “normal” demeanour when he left home to collect dinner.

Patrick spoke briefly with Lindsay by phone while he was at the pharmacy. When he returned home, he found her lying in the backyard with cuts on her wrists and neck. She told him she had tried to kill herself.

He then asked where the children were. Lindsay told him they were in the basement, where he found the three children with exercise bands tied around their necks.

Several witnesses, including Patrick, also testified that Lindsay later spoke from hospital about hearing a man’s voice telling her that if she did not act, she would lose her chance.

President of the Unites States (US) Donald Trump also commented on the case while speaking to reporters at the White House.

Asked whether he had followed the trial, Trump called it a “horrible tragedy” and a “terrible situation”. “I assume there’s going to be another trial,” Trump said. “She did a horrible, horrible thing. Can’t be worse.”

Clancy remains in custody at a state hospital and is due back in court for a status hearing on September 29.

If prosecutors retry and convict her of murder, she could face a life sentence. If a court finds her not guilty by reason of insanity, she could be committed to a state psychiatric hospital for evaluation, with her commitment subject to regular court review.