Constance Margaret Sirois was born on March 26, 1929, in Oakland, Maine. She was abandoned by her birth parents when she was very young. Later, she was adopted by the Sirois family. People who lived nearby described her as a pretty girl. However, she was also seen as moody at times.

In 1946, when Constance was 17 years old, she married Carl Marion Fisher. Carl was 24 years old and a veteran of World War II. He worked at a car shop related to the Maine Central Railroad. After marrying, they moved to a small home in Waterville, Maine. The couple had three children over the years: Richard, who was born in 1947, Daniel, born in 1948, and Deborah Kay, born in 1953.

On March 8, 1954, Carl Fisher returned home from work and found the door locked. Concerned, he called Dr. Richard Chasse and together they broke into the house. Inside, Carl discovered the bodies of his two children, Daniel and Deborah, in their beds. In the bathroom, he found his eldest son Richard drowned in the bathtub. Frantic and unable to locate his wife, he contacted the authorities. When the police searched the house, they found Constance hidden under a bed, unconscious from a suicide attempt after drinking shampoo. A suicide note explained that she had drowned the children to "save them from evil," claiming God had commanded her to do so.

Constance was arrested and charged with murder. The community was shocked by her actions. After a psychiatric examination, she was found to have paranoid schizophrenia and deemed unfit for trial. She was sent to Augusta State Hospital for treatment. While there, she claimed she had drowned her children because she wanted someone to care for her. Treatment involved insulin injections and hormones, which sometimes caused seizures. After a year, she showed improvement and was released to her husband's custody on March 6, 1959. The couple had three more children: Kathleen, Michael, and Natalie.

On June 30, 1966, Carl returned home to find their 9-month-old daughter Natalie drowned in the bathtub. He ran to a neighbor's house to call the police. Authorities found Michael and Kathleen dead in their beds. Constance was discovered in her own bed, unconscious from a pill overdose. This incident drew parallels to the earlier tragedy. She was taken to Thayer Hospital, then brought to Skowhegan for legal proceedings. Authorities sought to charge her with murder, but she was not required to undergo psychiatric treatment during her time in custody.

During a psychiatric evaluation, Constance was deemed competent to stand trial. She was charged with the murders of Kathleen, Michael, and Natalie. At court, she pleaded not guilty by reason of insanity. Testimony revealed that she had clear and coherent responses during interrogations. Despite efforts to secure a conviction, her defense argued she was insane, and the judge confined her to Augusta State Hospital for life.

Constance behaved well in the hospital until her husband stopped visiting her in 1973. Shortly after, she escaped, prompting a search by hospital staff and local authorities. On October 9, hunters found a body in the Kennebec River, which was identified as Constance. Her death was ruled an accidental drowning, likely occurring on the day she escaped. She was buried in the family grave plot in Waterville. When her husband died in 1990, he was buried there as well, alongside their six children.