The Montreal mother accused in the deaths of her three daughters and her husband's first wife admitted in a Kingston, Ont., court Thursday to lying to police after her arrest.

Crown prosecutor Gerard Laarhuis questioned Tooba Yahya, 41, about her account of the night of the four deaths that she gave to police after her arrest. He read a portion of the transcript in which Yahya denies that the family had ever been at the Kingston Mills Locks before police took them there on July 18.

The interviewing officer knew the denial wasn't true, as the accused were heard on an intercept on their way home July 18 discussing three times they had been at the locks.

Laarhuis brought up points in the transcript of the police interview with Yahya in which she described portions of the area around the locks.

"You told (the officer) that because that's what you remember," Laarhuis said.

Yahya responded: "I just lied to him. I told him that. I made that thing in order that he will leave me and I will get rid of him and he will not accuse me of lying 100 times."

Laarhuis asked Yahya if the pressure in the courtroom was the same as the pressure the day of her arrest. She said the pressure is the same but the "time is different."

"The pressure is not causing you to tell a lie here today is it?" Laarhuis asked.

Yahya responded, "No."

Yahya, who was in the witness box for a fourth day, her husband Mohammad Shafia, 59, and their eldest son Hamed, 21, have pleaded not guilty to four counts of first-degree murder.

Zainab, 19, Sahar, 17, and Geeti Shafia, 13, were found in a submerged car at the bottom of the Kingston Mills Locks in late June 2009 along with Mohammad Shafia's first wife, Rona Amir, 52.

Also Thursday, the prosection spent time questioning Yahya on her intentions during the police interrogation. During the interview, an officer presented Yahya with evidence from the scene, including broken glass that matched the family's Lexus SUV.

She responded during the interview by repeatedly questioning the officer about who was driving the vehicle.

In court, Laarhuis contended that Yahya's questions were meant to deflect blame from herself and Hamed, because in all previous accounts, Hamed had been behind the wheel of the SUV when the family arrived in Kingston.

"You're not being pressured to do or say anything — you are fixated on this point," Laarhuis said. "What proof do the police have as to who was driving?"

"I don't agree," Yahya responded.

Photos of daughters

On Wednesday, Yahya told the court she didn't feel dishonoured by pictures of her daughters wearing revealing clothing while with their boyfriends.

However, it was those photos, allegedly found after the girls' deaths, that sent her husband into a rage captured on a series of police wiretaps, Yahya said.

The Crown alleges the girls were killed because they brought shame and dishonour to the family.

On Wednesday, Yahya also faced questions about an account given to the court by a student who assisted the defence in preparation for the trial.

He earlier told the court that Hamed admitted he witnessed the accident, but didn't alert authorities because he was afraid of the wrath of his father. After dangling a rope in the canal and seeing no signs of life, he allegedly drove back to Montreal and told no one, according to the student's account.

'If it was an accident, he should have told us'

Yahya said if Hamed did indeed witness the deaths, he should have told his parents about the accident.

She said the first time she heard that account was in court. Yahya said he must have been frightened and under pressure.

"Are you defending Hamed now for not having told you?" Laarhuis asked.

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Tooba Yahya and her husband, Mohammad Shafia, arrive to the courthouse in Kingston, Ont., on Thursday (CBC)

"No," Yahya replied.

"If it was an accident, he should have told us … I'm upset with Hamed and my heart is bleeding. He should have told me what my children's death was."

Yahya and Shafia, who have both testified in their own defence, maintained that the girls and Amir went into the locks after their eldest daughter took the keys from her mother in the early morning on June 30.

They both testified that they have no idea how the car ended up in the canal, but concluded it must have been an accident with their unlicensed and inexperienced daughter Zainab at the wheel.

The court has not heard directly from Hamed Shafia.

The trial, which started in October, is now in its final phase and is scheduled to wrap up next week before the jury deliberates.