On Monday, Crown prosecutors called what is expected to be their final witness in a high-profile murder trial involving the deaths of four women from the same Montreal family.

The first-degree murder trial of Mohammad Shafia, his second wife Tooba Mohammad Yahya, and their adult son, Hamed Shafia, began in a Kingston, Ont., court in October.

Together, they are accused of killing four members of their family: Rona Mohammad, the first wife of Mohammad Shafia; as well as three of Shafia and Yahya's children, 19-year-old Zainab, 17-year-old Sahar and 13-year-old Geeti.

The four women were found dead two years ago, when police pulled a car out of the Rideau Canal with their bodies. Police soon zeroed in on the family members of the deceased as possible suspects.

Weeks after the victims' bodies were found, Shafia, his wife and his son, were arrested and charged with four counts of first-degree murder.

The accused have maintained that the deaths of Shafia's first wife and three daughters was some sort of accident. They have each pleaded not guilty to the charges.

The Crown's final witness is an expert on honour crimes, a choice CTV's Genevieve Beauchemin said was related to the prosecution's belief that family honour was the motive for the killings.

"The reason that they are talking so much about honour crimes is the Crown has alleged that this case hinges on an honour killing," Beauchemin reported from Kingston.

According to the Crown, the four victims were perceived to have dishonoured their family "by having boyfriends, by dressing more provocatively, by being more rebellious in some way," Beauchemin said.

During the trial, jurors have been hearing about Mohammad Shafia's personal belief that his family honour was of paramount importance to him.

On a wiretap recording played previously in court, Shafia is heard saying that nothing is more important to him than his honour.