The Alberta Court of Appeal is considering whether to double the six-year sentence handed an Edmonton foster mother convicted of killing a three-year-old boy in her care in 2007.

Lily Choy was convicted of manslaughter in 2011 four years after the toddler died of massive head trauma.

Today Crown prosecutor Joanne Dartana argued Choy's sentence is much too light and does not take into account the abuse leading up to the  fatal injury.

The court heard that Choy abused the child before his death, spanking him, making him march up and down the stairs at midnight, and leaving him wearing only a diaper in a unheated garage in the winter.

The sentence also doesn't reflect that Choy is a registered nurse and must have known her actions could cause the boy's death, Dartana said..

However Choy's lawyer Mona Duckett said it was "nonsensical" to suggest the appeal court justices are in a better position to weigh the evidence than the trial judge who listened to all the witnesses.

Choy appeared by closed circuit television from a prison in British Columbia.

The appeal court has reserved its decision. 

with files from CBC's Janice Johnston