An autopsy carried out by the Medical Examiner's office on Friday confirmed the mother and child died of carbon monoxide poisoning.
The Calgary Police Service were alerted to the deaths when emergency crews were called to a condominium in Calgary's northwest Thursday night after a man came home to find his wife and son dead.
Police Insp. Paul Stacey says the crews detected carbon monoxide in the house.
"We called the fire department out and ... they did have to smash some windows out to help air it out," Stacey said Friday. "Whether that is the cause of death or not, we're not sure and we won't know until after the autopsy."
Police say the bodies were discovered on the second floor and the deaths were not the result of an accident.
Police say they discovered a suicide note from the mom, Yu Mei Lai, in the home. Updated story soon @calgaryherald— Stephane Massinon (@stephmassinon) October 12, 2012
Calgary's major crimes unit has been called to investigate, but officers are not looking for suspects.
Grief counsellors are being made available at the school the boy attended.
-With Files from CP
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