MONTREAL -- Most parents can't stand to think about what the mother of the two Carpentier sisters has gone through in the last 10 days. Eleven-year-old Norah and six-year-old Romy were found dead on Saturday after going out with their father a few days earlier.

The two parents are no longer a couple. Not much is known about what led up to the girls' deaths, except that family reported to police in the days after their disappearance that they believed the girls' safety was at risk.

Jennifer Kagan is one of a few who has lived a similar nightmare. Her daughter, four-year-old Keira, died this February after she and her father, Kagan's ex-husband, fell from a cliff in an Ontario park.

Kagan believes her child's death was a murder-suicide carried out by her ex-husband on the final weekend before he was about to lose unsupervised visits with the girl.

While there may end up being few similarities between the two cases, Kagan says she wants people and the courts to take seriously how much of a danger parents can pose to their own children. 

"Just as I was fearful for my own safety during the marriage... I was quite fearful for the safety of my daughter," she said in an interview with CTV News.

"My ex-husband had even gone so far as to threaten me during the marriage that if I left him, he would make sure that I would pay and never see our daughter again."

He said he would get their daughter taken away, but Kagan said it was also clear from her ex-husband's behaviour that her daughter was not physically safe with him.

As a husband he was physically violent, severely controlling and erratic, sometimes harming animals in front of his ex-wife as well. One time, she recalled, while she was pregnant, he forced her to watch him kill a litter of baby rabbits.

"All of these factors caused me grave concern," she said. "We begged and pleaded with the courts and expressed those concerns."

In court, however, her husband was granted unsupervised visits with Keira.

"The judge that presided over our trial didn't really let me testify to the abuse," Kagan said. "He would cut me off, and he said the abuse is not relevant to parenting and he was going to ignore it."

When the judge finally did agree Keira's father could not be with her alone, the decision only took effect a month later. It was during that month, on the final scheduled visit, that the girl died.

Among the changes she wants to see, Kagan believes that all judges who preside over family law cases need to have a background in family law (the judge on her case did not) and they need mandatory training on the dynamics of domestic violence.

She also wants an inquiry into her daughter's death so that the big-picture problems can be resolved--for other kids' sake.

"How can we prevent this from happening to one other child?" she said.

Watch the video above to see Jennifer Kagan's full interview.