The defense in the Lindsay Clancy filicide case called the defendant’s mother as one of its first witnesses Monday, after three weeks of prosecution evidence laid out, in often harrowing detail, events surrounding Clancy’s killing of her three children.

Under questioning from defense attorney David Reddington, Clancy’s mother, Paula Musgrove, testified that her daughter’s statements and actions had unsettled her in the months leading up to 24 January 2023.

Clancy, Musgrove testified to the court in Plymouth, Massachusetts, had asked if she could sleep in her mother’s bed and told her she felt the medication she had been prescribed for postpartum depression were “destroying” her mind.

Musgrove also disclosed that on one occasion her daughter had approached her and Lindsay’s former husband, Patrick Clancy, and said: “I want to tell you guys something”.

“She said she had thoughts of harming the children,” Musgrove testified.

Patrick has previously told the court of his former wife’s statement and said she told him she had no plans to hurt the kids. Jurors have heard testimony from Patrick that his wife told him after the killings, while in hospital, that she’d “heard a man’s voice telling her that if she didn’t do it now, she would lose her chance, or something like that”.

Lindsay’s mother also said she received a text from her daughter on 20 October, three months before the killings. “I’m really sick. Something is wrong,” Lindsay wrote, saying she didn’t know how she would get through each day, and that medicine had not helped.

“I don’t want to be alone,” Lindsay added in the text.

Musgrove went to her daughter’s home in Duxbury, Massachusetts, and stayed for a week. In the following months, Musgrove and her husband made repeated trips from their home in Connecticut.

“In November and December, it was not getting better,” Musgrove testified, adding that Lindsay was losing weight and becoming “paranoid”. Musgrove said her daughter had said “this wasn’t her mind” and said “this isn’t me. I just want to feel better and enjoy my kids again.”

Lindsay’s defense is seeking to show she was suffering from a broad array of depressive symptoms, for which she had sought psychiatric help in the months leading up to the killing. Reddington argues the killings were driven by postpartum mental illness and not an intentional act, as prosecutors contend, followed by an insincere suicide attempt.

Lindsay, 36, is charged with the murders of her children, Cora, five, Dawson, three and eight-month-old Callan. Lindsay does not deny she fatally strangled her children – but has pleaded not guilty to murder, by reason of insanity or, under Massachusetts statutes, a lack of criminal responsibility.

If convicted of first-degree murder Lindsay faces life in prison without parole. If jurors find her not guilty, due to lack of criminal responsibility or by reason of insanity, she would be committed to a state psychiatric hospital.

Allison Ozga, Lindsay’s sister, testified that in the months leading up to the killings she had learned that her sister was having suicidal thoughts. “She’s feeling numb, she’s feeling hopeless,” Ozga said.

Earlier Monday, the prosecution rested after calling Ian Whiffin, a digital forensic expert tasked with examining Lindsay’s cellphone to look at her search history, calls, text messages and health data.

Whiffin said that at 5pm on the night of the killings, Lindsay had climbed two flights of stairs and spoken by phone with her husband, who was then at a pharmacy collecting constipation medication and going to pick up a takeout.

In the days prior, Whiffin testified, Lindsay searched online for “how quickly does Wellbutrin work for depression”, giving a brand name for a medication used to treat major depression, and “ketamine for suicidal ideation”. Five days before killing the children, on 19 January, she searched “symptoms of postpartum psychosis” and “psychosis symptoms”.