RCMP say the male was 16 at the time of the attack, in which the woman was killed and the boy was injured so badly he needed to be airlifted to hospital in Edmonton.
The perpetrator's sentencing has been scheduled for Jan. 10, 2013.
Details of what happened have always been sketchy because police have never released the woman's name or her relationship to the child.
They have only said they ended up going to the woman's home after finding her car abandoned with the engine still running after it had struck several parked cars.
They have also said the child has since been released from hospital and is recovering with family.