MONTREAL -- Martin Carpentier and his two daughters, Romy and Norah, were already dead by the time a Quebec Amber alert was triggered for the missing family, Quebec provincial police have confirmed, saying the girls' death was a double homicide.

Surete du Quebec spokesperson Guy Lapointe laid out the sequence of events in a news conference Wednesday afternoon, saying the criminal investigation into the puzzling incident that took place in Saint-Apollinaire, near Quebec City, is now over. The coroner's investigation continues.

The tragedy began with a car accident on the evening of July 8. Based on the investigation, police say the car crash was not a deliberate action and that Martin Carpentier in fact tried to gain control of the vehicle without success.

Prior to the crash, there was no indication of what would later unfold: the father and his daughters had gone out for ice cream. Police found a cone inside the car.

Up until the car crash, police say the man's behaviour was considered normal, and no one from his family was concerned he was a threat to his daughters. Police would not speculate on what transpired after the crash.

"As to what was going on in his mind? I don't want to go there," said Lapointe.

After the crash, witnesses say they saw the family running into the woods. They were never seen alive again.

Putting the pieces together, police now say that shortly afterwards, Martin Carpentier broke into a trailer about 1.7 kilometres from the site of the crash. Investigators say they believe that while he was the only person who entered the trailer, his daughters were with him at the time.

The girls' bodies were found 750 metres away. Lapointe said they were killed soon after with a blunt object. He would not elaborate on the manner of their deaths.

Following an extended manhunt with helicopters, drones, police dogs, ATVs and searchers on foot, the girls' bodies were found on July 11. Their deaths are considered a double homicide.

The story came to a close on the evening of July 21, when Carpentier's body was found some 5.5 kilometres from the car crash.

Police say that though the case unfolded over nearly two weeks, all of the events in fact took place within a very short time frame, said Lapointe.

By dawn on July 9, all three were dead.

The Amber alert was only triggered on the afternoon of July 9. Police say the reason they did not trigger the alert sooner was that they had no reason to believe Martin Carpentier would harm his children.

"We were worried" about their disappearance, said Lapointe. "But the worry wasn't about how the father would act toward his daughters."

Police say that in retrospect, they would not have set off an Amber alert sooner, because the element of kidnapping was not there based on the information they had at the time.

"We believe everything that could have been done was done, especially considering how fast the tragedy unfolded, unfortunately," he said.