The murder trial of Massachusetts mother Lindsay Clancy has divided public opinion in the United States after a jury failed to reach a unanimous verdict and a judge declared a mistrial.

Clancy, a 36-year-old nurse, was charged with murdering her three children. Her defence argued that she was experiencing postpartum psychosis and could not be held criminally responsible. Prosecutors alleged that the killings were intentional and calculated.

Jurors heard testimony from dozens of witnesses, including more than 10 experts on Clancy’s mental and postpartum health. They deliberated for about 40 hours over seven days before the judge declared the mistrial on Friday.

Debate over mental health and responsibility

The case has prompted wider debate over postpartum mental health, criminal responsibility and the limits of public sympathy for parents accused of harming their children.

Clancy said she experienced hallucinations and delusions before strangling her children — five-year-old Cora, three-year-old Dawson and eight-month-old Callan — and then jumping from a second-floor window, leaving her paralysed.

Her family testified about what they described as a deterioration in her mental state before the deaths. The court also heard that Clancy had sought help from medical professionals, visited an emergency room and called a suicide hotline.

Some expert testimony challenged the defence’s account. Jennifer Tufts, who treated Clancy during more than a dozen sessions over five months, testified that she had not observed signs of psychosis. Psychiatrist Avram Mack testified that the American Psychiatric Association did not recognise postpartum psychosis as a diagnosis.

Supporters outside the courthouse said the case had highlighted the mental health struggles faced by mothers. Others argued that mental illness could not excuse the killing of children and that Clancy should be held accountable.

The disagreement was also visible online and among people attending the trial. Supporters, many wearing pink, gathered outside the courthouse, while others called for justice for the children and criticised what they described as excessive sympathy for Clancy.

The case also led to online attacks and allegations involving Clancy’s former husband, Patrick Clancy. His lawyers said he had suffered an “unspeakable and unimaginable loss” and that the tragedy had been compounded by false and defamatory public statements.

Clancy’s future remains unclear following the mistrial. A hearing expected at the end of the month could determine whether prosecutors pursue a second trial or seek a plea agreement. In the meantime, the debate over mental illness, motherhood and criminal responsibility is likely to continue.