KINGSTON, Ont. - An Ontario court is hearing that three sisters allegedly killed by their family were "like political prisoners."

Three teenage sisters, Zainab, 19, Sahar, 17, and Geeti Shafia, 13, along with one of their father's two wives, were found dead inside a submerged car in the Rideau Canal in June 2009.

Their parents -- Tooba Mohammad Yahya, 41, and Mohammad Shafia, 58 -- and their brother Hamed, 20, are each charged with four counts of first-degree murder in their deaths.

A relative is telling court that Zainab wanted to get married to her Pakistani boyfriend in part to sacrifice herself so her sisters could have more freedoms.

The relative, who can't be named, says Shafia was not happy about the marriage, and told him if he had not been away on business at the time he would have killed her.

Court has heard Zainab did marry her boyfriend, but her family made her get it annulled the next day because it brought shame upon them.