KINGSTON, Ont. - Troubling questions about the mysterious case of four Montreal women found dead in a car at the bottom of the Rideau Canal came back to the fore Wednesday after unconfirmed media reports said arrests had been made in the case.

Kingston police Const. Michael Menor would only say that a news conference scheduled for Thursday would "update" the investigation into the deaths of 19-year-old Zainab Shafia, her two sisters and 50-year-old caregiver Rona Amir Mohammed.

As for the unsourced media reports of the arrests, Menor said, "We're not confirming or denying it at this point."

He also refused to say whether Kingston officers had been in Montreal, but said "I believe some of this information relative to the case will be available (Thursday)."

Shafia and her sisters Sahar, 17, and Getti, 13, were originally from the Afghan capital of Kabul, as was Mohammed, who helped raise the girls. They moved to Canada two years ago after a period spent living in the Middle Eastern metropolis of Dubai.

Their father, Mohammed Shafee, has said the family was headed home after vacationing in Niagara Falls and had stopped for the night at a Kingston hotel.

Shafee said he awoke on the morning of June 30 to discover that one of the family's cars was missing from the hotel parking lot. The three girls and Amir Mohammed, Shafee's cousin, were also gone.

Zainab didn't have a driver's licence, her father said, but did have a fondness for taking his keys so she could start one of the cars.

In a tearful interview at his home shortly after the car was found, Shafee said he couldn't shake the feeling that the crash may have been the result of Zainab taking the family car without permission.

The women were found at the bottom of the Rideau Canal's lock in Kingston Mills and investigators originally described their deaths as "suspicious," although no evidence of foul play was disclosed.

Neither the official cause of death nor the results of autopsies have been disclosed.

Police were baffled by how the car left the road and ended up in three metres of water in the lock, which would be difficult for a car to access. At the time, police said they weren't certain who was in the driver's seat but confirmed all four females were in the vehicle when it was recovered.