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 identified the dead as Yu-Mei Lai and Kevin Liu.
The medical examiner says the mother committed suicide, while the boy was the victim of a homicide.
Officers and fire crews detected carbon monoxide in the home and they had to smash windows to air out the townhouse.
Police say they are not releasing the source of the carbon monoxide or any other details about the deaths out of respect for the family.