The testimony came a day after jurors listened to the anguished 911 call made by Clancy's then-husband. He discovered the bodies of 3-year-old Dawson, 5-year-old Cora, and 8-month-old Callan after returning from an errand to their Massachusetts home in January 2023.
The murder trial has centered on Lindsay Clancy's mental state at the time. Her lawyers do not dispute that she killed the kids but say she had postpartum psychosis, a rare mental illness linked to the stress, sleep deprivation and hormonal changes that follow childbirth.
Prosecutors say Clancy, a former labor and delivery nurse at Massachusetts General Hospital, acted intentionally and is criminally responsible for the deaths.
Patrick Clancy has said in interviews that he forgives his ex-wife, whom he viewed as ill rather than evil. The trial marks the first time he has seen Lindsay Clancy since the killings.
Officers Stephen Hall and Brian Josephine of the Duxbury Police Department, in the coastal town south of Boston, were both separately dispatched to the house that evening. They arrived before Patrick Clancy realized his children had been strangled with exercise bands in the basement.
Hall said Patrick Clancy was yelling for help from behind the house, where his wife lay in the snow, drifting in and out of consciousness. Lindsay Clancy remains paralyzed from the waist down after she jumped from the home's second-story window and used multiple methods to try to kill herself.
As the officers tended to her, Patrick Clancy rushed into the house. He testified earlier this week that his wife told him the kids were in the basement, but didn't say they were dead. He let out a loud scream, the officers testified.
"I can't wake them up - I can't get them up!" he frantically told the officers when they ran downstairs. Only 8-month-old Callan had a faint pulse, Josephine testified.
"Based on my training experience from previous incidents, I knew it wasn't going to be good," Josephine said. They began rendering aid with help from firefighters.
PJ Hussey, a fire department supervisor, had arrived in time to glimpse through a basement window as Patrick Clancy tried to remove an exercise band from his child's neck.
"It turned very chaotic very quickly" as more ambulances were rushed to the home, Hussey testified.
Lindsay Clancy's lawyer said in opening arguments Monday that she had bipolar disorder, and that antidepressants prescribed after the birth of her third child worsened her condition. On the day she strangled them, she said she heard a voice telling her, "This is your last chance. Kill the children so you can kill yourself," according to her lawyer.
During the first two days of the trial, Patrick Clancy testified about his wife's deteriorating mental health in the months leading up to the killings. He said she told him about intrusive thoughts of harming the children and thoughts of suicide.
Lindsay Clancy had sought care from experts in postpartum mood disorders, was put on multiple psychiatric medications, and when nothing worked, checked in to a psychiatric hospital. She killed the children 19 days after she was discharged.
If convicted of murder, she faces life in prison without parole. If found not guilty due to a lack of criminal responsibility, she would be committed to a state mental health facility.
If you are experiencing suicidal, substance use or other mental health crises please call or text the new three digit code at 988. You will reach a trained crisis counselor for free, 24 hours a day, seven days a week. You can also go to 988lifeline.org or dial the current toll free number 800-273-8255 [TALK].