A relative of the Shafia family has testified in court that weeks before three sisters were found dead inside a submerged car, their father asked for help to drown one of his daughters.

The girls' parents and their brother returned to a Kingston, Ont., courtroom on Tuesday, after an unexpected medical emergency put their trial on hold last week.

Tooba Mohammad Yahya, 41, Mohammad Shafia, 58, and Hamed, 20, have pleaded not guilty to four counts of first-degree murder.

They're accused of killing the three girls and one of the father's two wives in late June of 2009. The bodies of Zainab, 19, Sahar, 17, Geeti Shafia, 13, and Rona Amir Mohammad, 50, were discovered in the Rideau Canal in Kingston, Ont.

A relative of the family who can't be identified told the court Tuesday that Mohammad Shafia called him several weeks before the victims were found dead and asked him to invite Yahya and Zainab to his home as part of an alleged plot to drown Zainab.

The relative testified that Mohammad Shafia called Zainab a prostitute and said that he did not approve of her going on the Internet, visiting the library, hanging out with friends or having a romantic relationship with a young Pakistani man.

Earlier on Tuesday, jurors resumed watching the interrogation video of Tooba Mohammad Yahya. Minutes after the video began playing in court, Mohammad Shafia buried his face in his hands and began to cry.

Prior to their deaths, the victims had lived together with the three accused in the same Montreal household. Rona Amir Mohammad and Yahya were both considered the wives of Mohammad Shafia in a polygamous marriage that had existed for years.

The family was originally from Afghanistan but relocated to Pakistan in 1992. They then moved to Dubai and Australia before arriving in Canada in 2007.

The Crown alleges that all four victims were murdered to protect family honour.

In the latter half of the interrogation video, shown in court on Tuesday, a police officer suggests the victims were unconscious when the vehicle they were in plunged into the canal.

The defendants originally told police that Zainab took the keys to the vehicle when they were stopped at a motel in Kingston, and that she must have driven it into the canal.

However, in the interrogation video Yahya eventually tells the officer that she, her husband and her son were present when the car went into the water, but that she fainted and her son may have fainted as well.

The high-profile murder trial began last month, but came to an abrupt halt last Thursday when the judge informed the court that one of the accused had suffered a "fairly serious" medical emergency.

While the judge did not say who was ill, Mohammad Shafia was the only one of the accused who was missing from the courtroom last Thursday.

Before the trial resumed on Tuesday, crime reporter Rob Tripp said Shafia's lawyer had indicated his client was on the mend.

With files from The Canadian Press