Arguments were heard today in Quebec's Court of Appeal in the case of Guy Turcotte, the Quebec cardiologist who was found not criminally responsible for stabbing his two young children to death.

The Crown is requesting the 2011 jury decision be annulled and a new trial ordered. The prosecutor argued that the judge in the first trial should have never even given the jury the option of finding Turcotte not criminally responsible.

The doctor from Saint-Jérôme, Que., admitted to the February 2009 fatal stabbing of Anne-Sophie, 3, and Olivier, 5, and was housed for 46 months in the Pinel Psychiatric Institute before being released last December.

The Crown said there was a lack of evidence to support a defence of not criminally responsible for reason of mental illness, arguing instead that the killings were premeditated, intended as revenge against former partner Isabelle Gaston, who was having an affair. 

Turcotte's lawyer, Pierre Poupart, argued that he suffered from serious mental illness at the time and was intoxicated on windshield washer fluid as part of a suicide attempt.

Poupart argued that the trial was thorough and meticulous, and that the jury ultimately arrived at the right verdict.

Gaston is watching the case closely and was in court today to support the overturning of Turcotte's sentence. 

She said the case is weighing heavily on her, and that its outcome will greatly impact her life.

"The stress is coming out. For me, it's a big step for our justice system to repair, for me, what is the biggest injustice in my life," Gaston said.

She said the defence's argument that Turcotte was suicidal and therefore unable to not distinguish between good and bad sets a dangerous precedent.

"I think we're opening a door that is very dangerous," she said. 

If the verdict is annulled and Turcotte is found criminally responsible in a retrial, he would receive a mandatory life sentence, with no chance of parole for 25 years.

The three-judge panel is expected to announce a decision before the new year.