A cardiologist, charged in the murders of his two children, appeared at the St. Jerome courthouse for a preliminary hearing on Monday.

Dr. Guy Turcotte, 37, has been behind bars since last February after five-year-old Olivier and three-year-old Anne-Sophie were found dead in a home in Piedmont, about 60 kilometres northwest of Montreal. Turcotte was also in the house, suffering from an apparent drug overdose.

Police said there were signs of violence on the children's bodies.

Monday's court proceedings were to determine if there is enough evidence to go to trial, said CTV Montreal reporter Stephane Giroux.

"The purpose of a preliminary inquiry is to test the evidence, or see where the case is going before the actual trial – which is why the prosecution and defense usually agree to a publication ban so a potential jury will not be contaminated by whatever they hear in the media," Giroux said.

Mother takes stand

Turcotte's mother, Marguerite Fournier, spent the morning on the stand and broke down in tears several times during her testimony.

She never exchanged looks with her son in the prisoner's box.

Turcotte took notes, and could also be seen crying on several occasions.

Several police investigators also took the stand, and Turcotte's ex-wife is also expected to testify during the week-long hearing.

If the judge is satisfied that the case is solid, he will send Turcotte to trial.

The case is not likely to focus on whether Turcotte in fact murdered his children, but rather, if he was sane or not when the tragedy unfolded.

If found guilty, Turcotte could face 25 years in prison.