Such an attack is a very rare occurrence and not normal grizzly behaviour, said Ryan Hennings, the manager of enforcement and compliance with the Conservation Officer Services Branch.
"This is very strange," Hennings said Monday. "At this point we're still trying to determine what happened and why."
The attack occurred Saturday outside the small community of Johnsons Crossing about 140 kilometres southeast of Whitehorse.
The Yukon Coroners Service said a family dog alerted the couple that a bear was on the property. The man ran to grab his rifle while the bear went through the window, a news release from the coroners' office said.
The husband and wife ran outside while the bear gave chase and caught the woman. The man managed to kill the animal and get his wife to the closest medical centre.
Claudia Huber, 42, died at the Teslin Medical Centre despite attempts to resuscitate her, the coroner said.
Hennings said the male grizzly was about 25 years old, considered the upper age limit in the wild. The animal was also underweight, at about 170 kilograms, compared to an average weight of an adult male of 200 to 225 kilograms.
"He was in poor condition, but he wasn't starving. He wasn't emaciated at this point," Hennings said. "He hadn't put on the fat reserves over the summer to hibernate. That's why he was still out at this time of year."
But Hennings said even hunger didn't explain such aggressive behaviour by a grizzly and there was nothing to entice the bear to the home.
"We found no obvious attractants that the property owner may have left around. In fact, we were very impressed with the care and management of bear attractants at this property," he said. "There was not even a barbecue on the porch."
Hennings said that's what makes it even more necessary to understand what set the grizzly off.
It's getting cold in the area and there's no vegetation left for bears. Hennings said most bruins in the area are hibernating.
A necropsy has been completed on the grizzly and they're waiting for tissue samples to be analyzed to try and fit more of the puzzle together, he said.
The coroner said an autopsy has been scheduled for this week on the woman's body.
(CKRW, The Canadian Press)