The physical evidence connected to the deaths of four family members found in the Rideau Canal proves that they were murdered, the prosecutor at the Shafia trial says.

"This evidence alone establishes beyond a reasonable doubt that what happened to the girls was no accident. It was murder," Laurie Lacelle told the jury Wednesday as the Crown started its closing arguments.

Tooba Yahya, 42, and husband Mohammad Shafia, 59, and their son Hamed Shafia, 21, are each accused of four counts of first-degree murder in the deaths of three Shafia sisters and the elder Shafia's first wife in a polygamous marriage.

Prosecutor Laurie Lacelle makes her final summation to the jury, saying that the evidence proves that the women were murdered. (Mike McLaughlin)

Zainab, 19, Sahar, 17, and Geeti Shafia, 13, along with Rona Amir, 52, were found drowned in a submerged Nissan in the Kingston Mills lock in eastern Ontario in June 2009.

Lacelle went through the evidence that linked the family's Lexus to the site where the four family members died, and suggested the only explanation for why pieces of the car's headlight were found there was that it had pushed the Nissan sedan into the water.

Addressing Hamed's account of the incident —that the car went in on its own while the driver was trying to turn around — she said: "Hamed has too many credibility problems at this point," for anyone to believe it was an accident.

Earlier, the lawyer representing Hamed Shafia had said his client is guilty of being "stupid" but not of murder.

Patrick McCann told the jury the account Shafia gave to a private investigator — that he followed the girls to the Kingston Mills locks, that they went in by accident and that he didn't call 911 or tell anyone because he was afraid of his father's reaction —was the truth.

"Hamed is guilty of being stupid — morally blameworthy — but other than that, he is not responsible for the girls' deaths, nor were his parents," McCann said. "It's time to put an end to this Kafkaesque [episode] they've been going through for the past two and a half years, since the night of June 30."

McCann also suggested that his client's sisters were manipulative, made up stories of abuse to get their way and that any testimony about their claims was unreliable.

McCann explained why they could not convict his client based on what he said was largely hearsay evidence.

He detailed how conversations recalled in court between the women and several witnesses was not reliable evidence. He went through each woman and described why any claims they made were either untruthful or unreliable.

'A bit spoiled'

"I don’t want to be standing here and criticizing someone who is deceased," McCann said, adding that the jury is being asked to assess the evidence they couldn’t hear from the source.

Referring to Zainab, McCann suggested she ran away to a shelter on April 2009 and tried to elicit sympathy from shelter workers because she wasn't being allowed to marry her boyfriend and not because she feared for her safety.

"A picture starts to emerge that she is a bit spoiled and used to getting her way. Maybe she is a bit headstrong … you're being asked to rely on statements she made to decide this is the basis, this is the reason she was murdered," McCann said.

He suggested the same case with Sahar, who told teachers she was fearful of her father and suffered abuse at home.

'Teenagers are always going to push to get their way. They want more freedom. They want to spend more time with friends.'— Patrick McCann, the lawyer representing Hamed Shafia

"With Sahar, we know that on at least two occasions she had no difficulty making up stories to get what she wanted," McCann said. "In that regard, I think it underlines the problems with her evidence and the hearsay aspect of it."

He said the girls used claims of abuse in a manipulative way.

"Teenagers are always going to push to get their way," he said. "They want more freedom. They want to spend more time with friends."

The Crown alleges the defendants killed the women because Sahar and Zainab Shafia were thought to have dishonoured the family by having boyfriends and living a modern lifestyle.

The defence maintains that the deaths were an accident, which occurred after eldest daughter Zainab took the keys to the family's Nissan sedan and embarked on a joyride with her sisters and Amir.

The defence has spent much of its time chipping away at the plausibility of the so-called honour killing motive.