A 47-year-old Laval mother has pleaded not guilty to murdering her two daughters.

Adele Sorella is accused of killing eight-year-old Sabrina and nine-year-old Amanda De Vito in her Laval home in March 2009.

The jury was shown photos of the girls lying next to each other in the playroom of their home, where police discovered the bodies. There were no marks of violence on them.

As the Crown pored over every detail of evidence, the girls' mother sat in the prisoners dock, occasionally wiping her eyes.

It's still unclear how they died, but prosecutors point out a hyperbaric chamber, used to treat one of the girls who suffered from juvenile arthritis, was seized by investigators.

Sorella is the ex-wife of Giuseppe De Vito, who's serving 15 years for his role in a major drug ring.

Purported to be a mobster, De Vito was on the lam when his daughters died, and did not show up for their funerals.

He was finally arrested in October 2010.

He had altered his appearance and was living with another woman in Laval

In court Monday, prosecutor told the jury that in the months before the deaths, Sorella tried several times to commit suicide.

They also went over everything police found in the house, including stacks of money hidden in several locations.

The case is expected to last up to two months.

Prosecutors say De Vito will be called to testify.

Meantime, Sorella remains free on bail.