Watch Live: Lindsay Clancy trial continues with contentious cross-examination, "What are you smiling for?"

The Lindsay Clancy trial resumed Monday in Plymouth Superior Court with a psychiatrist and psychologist taking the stand as testimony winds down in the Massachusetts murder case. Closing arguments could happen this week.

You can watch the Clancy trial live on CBS News Boston in the video player attached to this article, or on the WBZ-TV YouTube page when court is in session.

Dr. Avram Mack, a psychiatrist, was back on the stand Monday after testifying on Friday that he met with Clancy at Tewksbury Hospital in April, and she recalled telling her three children to "go to God" as she killed them in her Duxbury home. 

Mack was the first of three expected rebuttal witness called by the prosecution, as is protocol in insanity defense cases. 

The defense rested on Friday after calling its last witness, forensic psychiatrist Dr. Phillip Resnick, a key figure in the Andrea Yates trial. Resnick testified that Clancy reported feeling an "external force" take over her body before the murders.

Some people gathered outside court Monday morning wearing white to remember 5-year-old Cora, 3-year-old Dawson and 8-month-old Callan  

Pyschologist Dr. Kirk Heilbrun testifies

The second rebuttal witness called by the prosecution was Dr. Kirk Heilbrun, a forensic psychologist. He said he's testified in roughly 330 cases about competency to stand trial.

Heilbrun interviewed Clancy alongside Mack in April.

"She had a fairly limited mental health history before September 2022. She did experience some anxiety related to achievement, she was a very strong student in school and got straight As." Heilbrun testified. "And then she had some anxiety connected to her three pregnancies." 

He said Clancy got more anxious in mid-October when she started taking Zoloft.

"She immediately began to have some difficulty," Heilbrun said. There were some symptoms of depression, she immediately started having some really difficult insomnia and felt a lot of stress."

He said she started having "terrible" intrusive thoughts about harming herself in late November and early December, and later they would occasionally be about harming her children. But Heilbrun said she did not say she was "hearing voices."

"The way she described these, is they were not auditory hallucinations. Instead they were her own thoughts," he said.

Cross-examination of Dr. Avram Mack

Earlier Monday, Reddington wrapped up his contentious cross-examination of Mack, with the psychiatrist appearing in court via Zoom. Reddington said a judge in a previous case ruled that he was "unqualified" to give testimony, but Mack disagreed with that characterization.

"What are you smiling for? This is not funny, sir," Reddington asked Mack during questioning about the interview with Clancy.

There were several questions from Reddington about postpartum psychosis. Mack has testified that he believes Clancy was depressed but not experiencing psychosis at the time of the killings.

"Do you agree that postpartum psychosis is a legitimate disease or defect?" Reddington asked.

"When you have a symptom or sign of psychosis at any time, but particularly in the postpartum period, it is a legitimate finding and something to be concerned about and to treat," Mack answered.

Lindsay Clancy trial

Clancy has pleaded not guilty to charges of first-degree murder in the deaths of her three children.

The prosecution argues Clancy planned the murders and has suggested that her suicide attempt was not serious. The defense says she should not be held accountable because she was overmedicated and suffering from postpartum psychosis. 

Clancy faces life in prison without the possibility of parole if convicted of first-degree murder. If she's found not criminally responsible,  she will be sent to a state psychiatric hospital in Massachusetts.

If you or someone you know is in emotional distress or a suicidal crisis, you can reach the 988 Suicide & Crisis Lifeline by calling or texting 988. You can also chat with the 988 Suicide & Crisis Lifeline here.

For more information about mental healthcare resources and support, the National Alliance on Mental Illness HelpLine can be reached Monday through Friday, 10 a.m. to 10 p.m. ET, at 1-800-950-NAMI (6264) or email info@nami.org.