The Edmonton foster mother who was twice convicted of killing a three-year-old boy will remain in custody while waiting to see if she will be given a new trial.

Lily Choy is serving a 6-year sentence for at a women’s prison in British Columbia. In January 2007, she killed her foster son, who suffered a fatal brain injury when his head hit a toilet tank.

Choy was originally charged with second-degree murder, but was instead found guilty of the lesser charge of manslaughter in 2008.

The Alberta Court of Appeal ordered a new trial in the case and Choy was convicted again.

Her lawyer was in front of the appeals court again Wednesday, arguing for a third trial. Choy’s defence says the judge in the second trial made a mistake deciding Choy was not truthful while on the witness stand.

They also argue there were errors in assessing expert evidence.

The three-judge appeal court has reserved its decision.