The Montreal mother accused of the first-degree murder of her three daughters and her husband's first wife testified Tuesday morning in front of a packed Kingston, Ont., courtroom that she lied to police when she said she was at the scene where the alleged killings took place.

Tooba Yahya, 41, said she made up a story about being at the Kingston Mills lock, where the bodies of her daughters Zainab,19, Sahara, 17, and Geeti Shafia, 13, as well as first wife Rona Amir were found in June 2009 because she feared her co-accused son Hamed would be tortured by police.

On Tuesday, the Crown probed why she had such an understanding when RCMP officers said her son would "cool his heels" in jail and drink ice water.

"The way [the officer] was speaking in [the] Iranian language and the way I understood in my language, was that he'll be under freezing water," Yahya testified Tuesday.

As a result, she told police on July 22, 2009, that she had been at the scene when the car carrying the four females went into the water — but fainted after she heard a splash and couldn't recall anything beyond that.

Yahya said that she realized her error later and tried to explain her mistake to police the next day.

"I was thinking I have to say to police I lied and I have done that for Hamed and because of that nothing good will come out of it," she said.

Accused have pleaded not guilty

Yahya has been charged along with her husband, Mohammad Shafia, 59, and her son in the first-degree murder of the four females. The Crown contends the females were victims of so-called honour killings.

The accused have pleaded not guilty.

Yahya's statement that she was at the Kingston lock deviates from the one the family originally told police — that daughter Zainab had taken the keys to the car at the hotel where the family was staying and that was the last time anyone saw the drowning victims. The accused have said they were in their beds at the hotel at the time investigators believe the car went into the water.

On Tuesday, Yahya also sought to downplay wiretap evidence that recorded her husband saying he would cut the girls with a cleaver if they ever returned to life and "may the devil shit on their graves."

She said Shafia was simply angry because he had uncovered photos of the girls after their deaths with their boyfriends and wearing what he considered to be inappropriate clothing. Yahya said he was using common Afghan expressions to vent his rage.

Yahya said the photos were discovered in a pink album several days after the bodies of the four females were found in the Kingston locks. Her husband's rage, she said, was a result of that discovery.

However, prosecutors asked Tuesday why Yahya and Shafia were seen during media interviews in the immediate aftermath of the deaths — and at least a few days before she claims to have found the pictures — with a nearly identical album.

Yahya responded by saying the family has a number of the exact same photo albums.

She also denied ever hearing about so-called honour killings

"In 21 years when I was in Afghanistan, I never see that a stupid mother or a stupid father do anything like this," she said, adding that honour cannot be restored with an act of violence.

Final 2 weeks of testimony

In her first day of testimony, Yahya denied all but one incident of physical abuse in the home. She also denied claims made during the prosecution's case that she and Rona Amir, Shafia's first wife in the polygamous marriage, were rivals. She said she was close with Amir, and the pair split household tasks.

She also testified the children had few restrictions placed on them, but were told they were not allowed to date until they had their high school diplomas.

Part of the Crown's case involved testimony from two of the girls' boyfriends in what were alleged to have been forbidden relationships.

The family moved to Montreal in 2007 after fleeing Afghanistan several years earlier.

Earlier in the trial, court heard that on the day of the drownings, the family had been returning to their home following a trip to Niagara Falls, Ont. They had stopped at a motel in Kingston for the night.

The high-profile trial began in October but was adjourned for three weeks over the holidays. It resumed Monday with Yahya in the witness box. The trial is expected to last another two weeks.

The Crown will continue its cross-examination of Yahya Wednesday morning.

With files from CBC's Dan Halton and Melinda Dalton