Autopsies on Thursday may shed light on how the bodies of four females from Quebec - three teenaged sisters and an older relative - came to be in a car found submerged in three metres of water at the bottom of a canal lock, northeast of Kingston, Ont.
"This is very, very strange, it just doesn't make any sense," said Constable Mike Menor of Kingston police.
"In my 20 years here I can't recall anything like it."
The names of the four were not immediately released, but police said the group comprised three sisters aged 13, 17, and 19, and a 50-year-old relative, all from the Saint-Léonard section of Montreal.
The group had apparently been vacationing in Toronto and was en route back to Quebec.
Their black 2004 four-door Nissan Sentra was discovered Tuesday morning in the northernmost Kingston Mills lock, part of a scenic waterway system popular with tourists that connects Lake Ontario to the mouth of the Rideau Canal.
At around 8 a.m., a Parks Canada employee noticed an oil slick forming on the surface of the water. After the car was discovered at the bottom of the lock, its back bumper facing an outer wall, police divers located the four bodies.
Extracting them from the Nissan took more than two hours, a process Constable Menor described as traumatic for the divers.
"One guy had trouble talking about it," he said.
A crane then lifted out the car, which was taken away for examination.
The condition of the bodies suggested the four had been submerged for eight to 10 hours, meaning the car would have been driven or pushed into the lock late at night.
But there is no ready explanation for how or why it came to be there, Constable Menor said.
"You'd really have to do some manoeuvering to get out to this spot," he said.
"It's a very difficult place to drive into, and there would be no need to do so."
The post-mortems today are expected to show the cause of death.
As things stand, police can only speculate as to whether the family drowned or was already dead when the car tipped into the water.
It was unclear whether the bodies showed any signs of injuries or were strapped in with seat belts when the vehicle was found.
Nor could Constable Menor say whether any of the four victims were known to police,
Detectives are anxious to interview anyone who may have seen the Nissan on the evening of Monday, June 29.
The identities of the four will likely be released Thursday or Friday, after next-of-kin have been notified