Prosecutor corners Lindsay Clancy's Catholic mother-in-law with 'mortal sin' question

Prosecutors played the faith card Tuesday, asking Lindsay Clancy's Catholic mother-in-law if she knew murder is a mortal sin. It was part of their push to show Clancy knew what she was doing when she killed her three children, not that she was in postpartum psychosis as the defense claims.

Lindsay Clancy, 36, is charged with three counts of first-degree murder in the deaths of her three children - Cora, Dawson and Callan, all under 6 years old, who were found strangled in the family's Duxbury home in 2023. Prosecutors concluded their case Monday morning.

On Tuesday, Assistant District Attorney Shanan Buckingham asked Susan Clancy, Lindsay's mother-in-law and a Catholic, if she knew murder was a "mortal sin."

Susan Clancy, the former mother-in-law of Lindsay Clancy, testifies during Lindsay Clancy's murder trial in Plymouth Mass., Tuesday Aug. 18, 2026 in Plymouth, Mass.

Susan Clancy didn't answer the question, and Judge William Sullivan immediately called a sidebar and struck the remark from the record.

Susan Clancy told jurors Tuesday she had concerns about Lindsay's mental health during the 2022 holiday season, though she described her as a devoted mother.

"Lindsay was struggling. We were all very concerned," Susan Clancy said. "She was very nurturing, very loving. She was a wonderful mother. Wonderful."

Susan Clancy said she began seeing a decline in Lindsay's mental health in November 2022.

"She reached out to me in November and told me that she felt unwell," Susan Clancy said. "She felt ... mostly she had insomnia. She was losing her appetite. She was very anxious and sad.

"She was begging for help."

Paula Musgrove, mother of Lindsay Clancy, enters the courtroom to take the witness stand during her daughter's murder trial in Plymouth Superior Court, in Plymouth, Mass., Monday, Aug. 17, 2026.

Paula Musgrove, Lindsay Clancy's mother, also told jurors about the mental health problems. In an Oct. 20, 2022, text message, Lindsay Clancy asked her mother for help.

"Mom, will you please come up and stay with me for a bit? I'm really sick. Something is wrong. I had horrible insomnia all night, and I just don't know how I am going to get through the day. ... It's just really scary, and I don't want to be alone," the text read.

Musgrove said she wasn't concerned about the children's safety.

Lindsay Clancy's defense team will continue presenting its case Wednesday morning as her defense team seeks to convince jurors that she was suffering from severe postpartum psychosis when she killed her children.