Quebec coroner Renee Roussel will perform the autopsies on Noemi and Audrey Belanger, whose bodies arrived earlier Friday from Thailand. The procedure will be performed at a Montreal laboratory.
The 20- and 26-year-old Quebec women were found dead at a beach resort in the Phi Phi islands on June 15, under mysterious circumstances.
Police have said the women didn't appear to have been murdered and evidence suggests they may have been accidentally poisoned.
Experts say it might be some time before the family can know for sure what caused the deaths, and whether a toxic substance was indeed involved.
One says the process should shed additional light on what happened, after a preliminary autopsy was performed in Thailand.
"We don't know how they proceeded in Thailand but, one thing is certain, it's not the first time that a second autopsy is performed in Quebec," said Charles Jodoin, a forensic expert. "If they're taking the time to do it, it's because they've been able to get meaningful results in the past."
The sisters grew up Pohenegamook, a town of about 3,000 in eastern Quebec near the Maine border, but studied in Quebec City.
Their bodies were embalmed before being transported to Quebec.
It could be weeks or months before the coroner reports the findings, a spokeswoman said. Genevieve Guilbault said the autopsy itself could take some time.
"The completion of autopsies can take hours or days, and the publication of the official report weeks or months," she said.
But Jodoin says when a pathologist has a good idea about the cause of death, he will often communicate it with the family to keep them in the know.
The embalming process can create some problems, Jodoin admits. Primarily, embalming consists of disinfecting the body and injecting it with a fluid to keep organs preserved.
"You have to look at each organ, examine the tissues to determine if there are signs of the cause of death, but all depends on the manner in which they proceeded in Thailand," Jodoin said.