Tooba Mohammad Yehya, left, her son Hamid Mohammad Shafia, centre, and his father Mohammad Shafia, right, are seen outside a Kingston, Ont., courthouse on Thursday. (CBC)

The father, mother and brother of three teenage girls from Montreal whose bodies were found in a submerged car in a Kingston, Ont., canal were charged Thursday with killing them and a woman believed to be the father's first wife.

Zainab Shafia, 19, Sahar Shafia, 17, and Geeti Shafia, 13, were found dead last month along with Rona Amir Mohammed, 50, in a submerged car at a Rideau Canal lock near Kingston.

Parents Mohammad Shafia and Tooba Mohammad Yehya and their son Hamid Mohammad Shafia, 18, have each been charged with four counts of first-degree murder and four counts of conspiracy to murder, Insp. Brian Begbie announced at a news conference at Kingston Police headquarters on Thursday.

The three, who live in the Montreal neighbourhood of St. Léonard, are being held in custody in Kingston while waiting for bail hearings.

This photo taken in the 1980s is said to show the wedding of Rona Amir Mohammed, left, and Mohammad Shafia, centre, in Afghanistan. The photo was sent to the media by email by a purported family member. (Canadian Press)The submerged black Nissan Sentra was discovered around 12:30 p.m. on June 30, the same day Mohammad Shafia went to the Kingston Police station to report that his daughters and a woman he said at the time was his cousin were missing, along with his vehicle. He was accompanied by his wife and son, said police.

Begbie said investigators have "cause to believe" the older woman found in the car was, in fact, Mohammad Shafia's first wife.

Police said that by the time the bodies were discovered, they had been in the water for as long as 12 hours.

The car's front end was up against the lock wall as if the vehicle had plunged in backward.

The father told police he discovered his car was missing after the family had stopped at a Kingston motel following a trip to Niagara Falls, Ont., the day before. The family had been travelling in two vehicles.

When they were told about the discovery of the submerged car, police said all three suspects spoke about their trip to Niagara Falls and Zainab's habit of taking the car without consent and without a driver's licence, a claim police say is untrue.

"Our investigation to date reveals that this allegation is false and that on the night in question, the Nissan was operated by a combination of the three accused persons," said Begbie.

Girls lived as 'Canadian teenagers'

The three Shafia sisters are seen in an undated family photo. (CBC)Police also said the son drove the family's second vehicle to Montreal in the early-morning hours of June 30 and returned to Kingston to accompany his parents to the police station. The couple have three more children — two daughters and a son — now in care of youth protection services in Montreal.

Both vehicles — the submerged Nissan and a Lexus SUV — are being examined by police, said Begbie.

Police said they are looking into whether the deaths were an "honour killing" — a tribal custom practiced in some parts of the world in which the majority of victims are women who are perceived to have brought shame to their family.

Kingston police Chief Stephen Tanner said he received an email from someone who is likely a relative of the family who claimed it was such a killing.

"That will form a part of the ongoing investigation," said Tanner. "There are family members in a variety of parts of the world and investigators will be following up with them.

"Whether that was a part of the motive within the family, based on one ... or more of the girls' behaviour is open to a little bit of speculation."

Tanner said the girls were living as "Canadian teenagers who have all the freedom and rights of expression of all Canadians."

Tarek Fatah, radio talk show host and founder of the Muslim Canadian Congress, said Tanner made a "very clear reference" to honour killings during the news conference when he discussed freedom of expression and the choices that young women in Canada, as Canadian citizens, have.

Mother 'distraught,' says lawyer

Yehya's lawyer, Lucie Joncas, told reporters outside court that the mother is grieving for her children.

"It's obvious my client is very emotionally distraught by the whole tragedy," Joncas said.

Waice Ferdoussi, who represents Shafia, said that his client was "very surprised" he was arrested and that they were a "close family."

"These are very severe charges, not a joke," he added.

The family, originally from Kabul, Afghanistan, spent 15 years in Dubai before moving to Montreal two years ago.

Tanner said other police agencies, including the Ontario Provincial Police, the RCMP, as well as Ottawa, Montreal and Toronto police forces, were involved in the investigation.

With files from The Canadian Press