Knowing she had only days to weeks left to live, Christine Hagan gave her daughter Jessica, 19, who had Down syndrome, a lethal dose of drugs in September.
On Thursday, Calgary police announced Jessica's death was a homicide but said no charges would be laid because her mother had recently died of cancer.
"We're just trying to get over the loss of two integral family members and we're strictly in the grieving process," Brian van Vliet, Christine's brother, told CBC News.
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Christine, who was in her 50s, was diagnosed with stage 4 pancreatic cancer in May and though she prayed for a miracle, she knew in her heart she didn't have long to live, according to her brother.
"She was weak and very, very ill and it was just a matter of days before her passing," van Vliet said. "Christine was always a family first person, very caring, very boisterous, giving, loving."
Van Vliet said he believes that in her final days, his sister was very upset about what she had done to her daughter.
Body found in home
Jessica was found dead inside her Cranston home on Sept. 8. Christine was also found in the home, in medical distress, and was taken to hospital and kept in "medical custody" until her death on Nov. 21.
The family is mourning both deaths while grappling with the information that Christine killed Jessica, according to van Vliet.
Adding to the family's torment was a recent Alberta Health Services privacy breach.
Dozens of staff at Calgary's South Health Campus were disciplined for accessing Jessica and Christine's personal health information, van Vliet confirmed on Thursday.
One employee was fired and 47 more were disciplined.