Human remains were found in two of the three euthanized bears after they were suspected of attacking and killing a woman, according to wildlife officials.
The body of the 39-year-old woman was found north of Durango in southwest Colorado on Friday.
Authorities suspected that she had been the victim of a rare bear attack because of bear droppings and hair found at the scene.
A team of dogs found a 10-year-old female black bear and two one-year-old cubs nearby. They were killed after they were suspected of attacking the woman and being able to attack someone else.
The human remains were found in the stomach of the sow and one of the calves during an autopsy on Saturday, Colorado Parks and Wildlife (CPW) said.
An initial examination by a pathologist showed the bears all appeared healthy, with no signs of illness and with adequate fat stores after the winter hibernation season, according to the agency.
He added that a microscopic examination of their body tissues and tests for rabies to find other possible reasons that could have caused the attack would take up to two weeks.
In announcing the autopsy results, Cory Chick, CPW Regional Director, said: “Our thoughts and prayers are with the boyfriend, family and friends of the woman we lost in this tragic event. . “
“We cannot determine with exact certainty how or why this attack took place, but it is important that the public does not blame this woman for this unfortunate and tragic event.”
The woman’s boyfriend returned home around 8:30 p.m. Friday and their dogs were outside, but she was missing after taking them for a walk.
He began to search and found his body an hour later on US Highway 550 near Trimble, a community north of Durango, and called emergency services.
An autopsy will take place on Tuesday.
The last fatal bear attack in Colorado was recorded in 2009 near Ouray – when a 74-year-old female was killed by a 394 lb (179 kg) male black bear.
An investigation found she illegally fed bears through her yard fence, CPW said.