"We'll go wherever the evidence leads us," said Barb McLintock of the BC Coroners Service.
"We will look into all possibilities ranging from postpartum depression to tragic accident but we will need to do much more work to come up with definitive answer."
The investigation will also look into the possibility of a fall caused by a medical condition of the 26-year-old mother, but that's considered less likely given the young age of the woman, said McLintock.
RCMP have said there was no third party involved in the incident.
Several witnesses called 911 Friday when they saw the mother and child in the water near the Condensory Bridge around 2:30 p.m. PT.
A helicopter spotted the baby boy on one side of the river. He was airlifted to hospital around 3 p.m., and remains in critical condition at BC Childrens' Hospital.
His mother was found and pulled from the water an hour later, according to police. She has since died.
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