This photo is said to show Rona Amir Mohammed, second from left, and Mohammad Shafia, centre, at their engagement ceremony in Afghanistan circa 1980. It was emailed to the media by a purported family member. (Canadian Press)

Siblings of the woman who died in a Rideau Canal lock near Kingston, Ont., told CBC News on Friday that their sister, Rona Amir Mohammed, feared for her life at one point in the days leading up to her death.

Wali Abdali and Diba Masoomi, who live in France, are the brother and sister of Rona Mohammed, 50, who was found dead in a submerged car on June 30, along with three other female victims: sisters Zainab Shafia, 19, Sahar Shafia, 17, and Geeti Shafia, 13, of Montreal's Saint-Léonard district.

The sisters' father, Mohammad Shafia, their mother, Tooba Mohammad Yehya, and their 18-year-old brother, Hamid Mohammad Shafia, have been charged with first-degree murder and conspiracy to commit murder in the four deaths.

Abdali and Masoomi told CBC News their sister, Rona, was in fact the first wife of Mohammed Shafia. They said Rona married Shafia 30 years ago in Afghanistan, but when she was unable to bear children, the siblings said Shafia took a second wife.

The three Shafia sisters whose bodies were found in the canal are seen in an undated family photo. (CBC)

They said Rona wanted a divorce, but Shafia was apparently not interested, and so he lived with two wives.

When the family moved to Dubai and later Montreal, the siblings said Rona went along. Abdali and Masoomi said Rona cared for the Shafia family's children as if they were her own.

Abdali and Masoomi said there was tension in the family in recent years. They said the 19-year-old daughter, Zainab Shafia, was dating someone of whom her parents did not approve, adding that Zainab apparently left the family home in Saint-Léonard for a week, which angered her parents.

Masoomi said Rona told her she overheard Mohammed Shafia talking to his wife about the idea of killing Zainab some weeks ago.

Masoomi said when she last spoke to Rona just before the family's trip to Niagara Falls, she said her sister was afraid for her life, but Masoomi tried to reassure her that she would be safe in a country such as Canada.

Abdali said after the deaths, he heard from Mohammed Shafia, who apparently cried on the phone and told him the deaths were an accident. Abdali and Masoomi said they've been in contact with Kingston police, and investigators said they would follow up on their information.