The case of Lindsay Clancy, a Massachusetts mother accused of killing her three young children in 2023, has ended without a verdict after a jury became deadlocked following weeks of testimony and deliberations.

Clancy, 36, was charged with killing her children — five-year-old Cora, three-year-old Dawson and eight-month-old Callan — at the family’s home in Duxbury, Massachusetts, on January 24, 2023.

The prosecution alleged that Clancy deliberately killed the children, while her defence argued that she was suffering from severe postpartum psychosis and other mental health problems that left her unable to understand or control her actions.

According to prosecutors and evidence presented during the trial, Clancy strangled the three children before attempting to take her own life by jumping from a window.

Cora and Dawson died shortly after being taken to hospital, while Callan, the youngest child, died several days later.

Clancy survived the suicide attempt and was subsequently charged with three counts of murder.

The case attracted widespread attention because of the circumstances surrounding the children’s deaths and the questions it raised about postpartum mental illness and criminal responsibility.

Clancy’s defence did not dispute that she was responsible for the physical acts that killed the children. Instead, her lawyers argued that she should not be held criminally responsible because she was experiencing severe postpartum psychosis.

Defence experts described a deteriorating mental state in the period leading up to the killings, including hallucinations and suicidal thoughts. Her lawyers argued that the illness affected her ability to understand the wrongfulness of what she was doing.

Prosecutors, however, argued that Clancy’s actions were deliberate and that she understood what she was doing and that it was wrong. The competing arguments over her mental state became the central issue at trial.

Postpartum psychosis is a rare but serious psychiatric emergency that can occur after childbirth. It can involve symptoms such as hallucinations, delusions, severe confusion, mania and rapidly changing mood.

The condition is different from the more common postpartum depression. Medical experts have stressed that postpartum psychosis requires urgent psychiatric assessment and treatment.

The Clancy case brought renewed public attention to the condition and to questions about whether warning signs of severe maternal mental illness are adequately recognised and treated.

After more than five weeks of testimony, the 12-member jury spent about seven days deliberating but repeatedly told Judge William Sullivan that it could not reach a unanimous decision.

The jury was ultimately deadlocked, prompting the judge to declare a mistrial on September 4.

Reports said the jury was divided 11-1 over whether Clancy should be held criminally responsible for the killings. The defence had unsuccessfully sought to have the holdout juror removed, but the request was rejected by the court and subsequently by the Massachusetts Supreme Judicial Court.

The mistrial does not mean Clancy has been acquitted. The murder charges remain in place, and prosecutors could decide to retry the case.

As of the latest reports, prosecutors had not announced whether they would pursue a second trial. Clancy remains in state custody, and another court hearing is scheduled for September 29.

The case has therefore entered a new phase, with prosecutors facing a decision over whether to bring the emotionally charged case before another jury.

Beyond the courtroom, the Clancy case has also renewed debate in the United States about postpartum psychosis, access to maternal mental-health treatment and how the justice system should assess criminal responsibility when severe mental illness is involved.