The bodies of 52 sled dogs have been pulled from a mass grave believed to contain the bodies of 100 sled dogs killed in Whistler, B.C., last year, according to the B.C. SPCA.

"In order to protect the integrity of the investigation and the evidence, I'm not going to go into great detail about what was found. However, I can report that as of today 52 dogs have been removed from the grave," Marcie Moriarty, head of cruelty investigations, told reporters Sunday in Whistler.

She said the excavation process is not complete and expects more bodies will be pulled from the grave in the coming days.

It's not clear, she said, whether criminal charges will be laid.

"The investigators are collecting forensic evidence and we will put that evidence before [the] Crown and it will be up to Crown counsel to make that determination."

Moriarty said the bodies that have been exhumed are being examined for evidence they may have suffered unnecessarily.

"Any sort of case where it could be established throats had been cut and bled out — that is not an acceptable method of killing an animal in Canada. If the animal was bludgeoned to death and didn't die instantly."

The B.C. SPCA hired a team of internationally recognized forensic experts with experience in the Robert Pickton pig farm murders as well as with mass graves in Rwanda, Afghanistan and Iraq.

The investigation could cost up to $225,000. The B.C. government has provided half that money but the rest will have to come from donations.

At Sunday's news conference, Moriarty defended the cost.

"I want to be clear: We would not have taken this step if it wasn't essential to proceeding with possible charges in this particular case. Our legal system requires proof of allegations, and in this case the forensic evidence was a key component," she said.

"While the scope of the sled dog investigation is significant, to ignore such disturbing allegations was really not an option. We're also an enforcement agency and we have a mandate to investigate complaints of animal cruelty that are brought to us."

Moriarty said it could take several weeks or even months before the evidence is processed. However, she said there are some new findings that will hopefully help develop a sled dog code of practice and improve the welfare of sled dogs throughout B.C.

The dogs were killed over a two-day period in April 2010 by Robert Fawcett, who described in graphic detail in a WorkSafeBC document how he had to cull the animals in front of each other because of the size of the cull.

Fawcett was the part owner of Howling Dog Tours, along with Whistler-based Outdoor Adventures, which used the sled dogs on its tours. Outdoor Adventures maintains it never sanctioned the killing of that many dogs, and did not take over the operation of Howling Dog Tours from Fawcett until a month after the slaughter.