Jury deliberations are set to resume on Friday morning in the trial of Lindsay Clancy, the Massachusetts woman charged with murder for strangling her three young children in 2023.

After more than four weeks of often emotional testimony in the high-profile case, the lawyers on each side made their closing arguments at the courthouse in Plymouth, Mass., on Thursday. It was their final opportunity to convince the jurors whether or not Ms. Clancy should be held criminally responsible for the children’s deaths.

Ms. Clancy does not deny that she killed the children at her home in Duxbury, Mass., an affluent Boston suburb, and has pursued an insanity defense. Her lawyer, Kevin Reddington, maintains that she was suffering from postpartum psychosis and had experienced auditory hallucinations of a man’s voice ordering her to kill her children and then herself.

Mr. Reddington described Ms. Clancy on Thursday as “a darn good mother” and a respected nurse who loved her children. He read from a long list of medications that had been prescribed to Ms. Clancy in the months before the killings, arguing that she had received “lousy medical care” when she sought help for her anxiety.

“This young lady is not guilty of the killing of her children,” Mr. Reddington said, “because she was suffering from a disease and defect.”

Earlier on Thursday, the judge, William Sullivan of Plymouth County Superior Court, had told the jurors that Ms. Clancy could not be held criminally responsible if she had a mental disease or defect that prevented her from controlling her actions, or from distinguishing right from wrong.

Jennifer Sprague, a prosecutor, used her closing argument to present the killings as a series of rationally made and premeditated choices. She called the killings an act of “extreme atrocity and cruelty” and described the horrific scene that Ms. Clancy had left behind.

“She left them discarded on the basement floor, like broken toys, because she was done playing the game,” Ms. Sprague said. “You know, to a moral certainty, she is guilty.”

Prosecutors have argued that Ms. Clancy plotted to get her then-husband, Patrick Clancy, out of the house on Jan. 24, 2023. Mr. Clancy returned home from picking up takeout food to find the children in the basement with exercise bands around their necks, he said during his testimony. Cora, 5, and Dawson, 3, were dead. Callan, 8 months, died days later.

Mr. Clancy also found Ms. Clancy lying injured in the backyard. She had cut her wrists and neck and jumped from a second-story window of the home in what her lawyers have called a suicide attempt, which left her partially paralyzed.

Ms. Clancy, 36, did not testify during the trial. The witnesses have included Ms. Clancy’s mother, her sister, her former mother-in-law, and several psychologists who treated Ms. Clancy before the killings or evaluated her afterward. The prosecution rested early last week after calling more than 70 witnesses, and the defense rested on Friday after calling 10.

Rebuttals, which give prosecutors an opportunity to respond to claims made by the defense, took up the last few days of the trial. The three rebuttal witnesses for the prosecution, all forensic psychologists, pointed to evidence that Ms. Clancy may not have been suffering from postpartum psychosis. In combative cross-examinations, Mr. Reddington questioned their expertise and at one point asked the judge to grant a mistrial after one of the witnesses mentioned the concept of “mortal sin” while discussing Ms. Clancy’s Catholic upbringing.

For much of the trial, a crowd of demonstrators has gathered outside the courtroom. Many were women who wore pink to support Ms. Clancy and to call attention to what they see as the health care system’s failures to address maternal mental health.

In her closing argument, Ms. Sprague said that the case was “not about our mental health system, or how it treats women.”

She added: “That’s a distraction to get you angry and passionate — about an important issue, but an issue that’s not on trial here.”

To secure a guilty verdict, the prosecutors must prove beyond a reasonable doubt that Ms. Clancy committed the crime, knew that the murders were wrong and had some control over her actions.

Judge Sullivan instructed the jury to choose among first-degree murder, second-degree murder and manslaughter if they find Ms. Clancy guilty. She faces life in prison without parole if convicted of first-degree murder.