British Columbia's Society for the Prevention of Cruelty to Animals is set to begin the grisly task of exhuming the remains of nearly 100 sled dogs allegedly killed last year and buried in a mass grave near Whistler, B.C.

The association has secured a warrant to exhume the animals as it probes allegations that up to 100 of them were slaughtered in April 2010. The work is expected to begin on Thursday and could take several days.

The agency said in a statement Sunday that it has assembled a team of forensic scientists, anthropologists and veterinarians to work on the case, some of whom had previously aided the investigation into serial killer Robert Pickton.

Team members have worked on identifying the victims of the Green River serial killings and the Hinton train disaster, and some have aided investigations into mass graves in such locations as Guatemala, Rwanda, Sri Lanka and Afghanistan.

"This is one of the largest and most complex investigations the BC SPCA has ever undertaken," Marcie Moriarty, general manager of cruelty investigation for the agency, said in a statement.

"Because of the length of time that has passed since the incident occurred, it is necessary to employ painstaking, state-of-the-art forensic techniques to gather the evidence needed to pursue animal cruelty charges in the case."

According to Moriarty, the cost of the excavation may top $225,000.

News of the purported cull surfaced in January after workers' compensation documents were leaked to the media. The documents outlined a claim by a worker who said he was experiencing post-traumatic stress after killing the dogs. The worker alleged the dogs were shot or had their throats cut over the course of two days.

The animals were under the control of a Howling Dog Tours. Another firm called Outdoor Adventures had a stake in the company when the cull took place, but insists it had no idea about the cull.

In the claim, the worker said he was ordered by his employer to kill the animals after business slowed in the wake of the 2010 Vancouver Olympics. Outdoor Adventures has denied that.

The allegations prompted outrage both in Canada and internationally, casting a dark cloud over the province's eco-tourism industry.

B.C.'s SPCA launched a criminal investigation into the matter under the Criminal Code of Canada, which sets higher standards for a conviction than does provincial legislation, an official with the association said.

The RCMP is also probing death threats related to the case.

Following the public outcry, the B.C. government appointed a task force to review the local dogsled industry. The task force published 10 recommendations last month, which include boosting penalties for animal cruelty, instituting standards for the sled-dog industry and increasing funding for B.C.'s SPCA.

Premier Christy Clark endorsed the report's recommendations after it was released and pledged to enact what she called the toughest animal cruelty legislation in the country.

Before the dig begins, debris will be cleared from the site and screened. Experts will then use lasers, probes, GPS and other measures to determine the grave's accurate measurements.

The team will then clear the top two inches of soil and lay down a grid.

Moriarty said in her statement that teams will dig through each section of the grid by hand, a process that will take three to four days.

All remains that are recovered will be photographed, examined and x-rayed before being refrigerated and transported to necropsies.

"This process will take time but we want to ensure that every relevant piece of evidence is presented to Crown," Moriarty said.

With files from The Canadian Press