A preliminary hearing began Tuesday for those accused of submerging a car in the Rideau Canal last summer, allegedly killing the four women inside. The process will take at least a month to complete.

Mohammad Shafia of Montreal is charged with first-degree murder, along with his wife Tooba and their son Hamed.

In what is now known as the "canal killings", the couple's three teenage daughters and Shafia's first wife were found inside a car under the water at the Kingston locks of the Rideau Canal.

Prosecutors say there is enough information to put the trio on trial.