This grizzly sow was captured the night after Lance Crosby was fatally mauled. DNA tests implicated the bear in his death, and she was later put down/NPS

Lance Crosby, out for a morning hike on a forested mountainside above the Lake development in Yellowstone National Park, apparently had little time to react when a sow grizzly charged him last summer, according to an investigation into his fatal mauling.

The 63-year-old tried to fend off the sow, but was no match for the 259-pound bear. An autopsy determined that blunt force trauma that damaged Mr. Crosby's brainstem quickly led to his death.

"Evidence at the site indicated that the attack and death occurred in a small area at the site of the cached body. There was no body drag trail, no disturbed ground indicating an attack path, no disturbed soil or vegetation indicating a struggle, no blood anywhere outside the body cache, and no clothing fragments or personal possessions found outside of the body burial cache," reads the report issued by the Board of Review appointed by the U.S. Fish and Wildlife Service. "All of this evidence and the fact that Mr. Crosby’s ball cap was found within 3 feet of his left foot on the cache suggest that the initial contact by the bear and the death of Mr. Crosby occurred at the location where the body was found."

The Montanan's death last August 6 occurred near a trail on Elephant Back Mountain popular with the public and park employees who lived at Lake. The general area also was popular with bears: "In 2015 up to August 6, the likely date of the fatality, 327 reports of grizzly bear activity and 40 reports of black bear activity were recorded within a 30-km radius of the fatality site," the investigation noted.

As officials suggested last August, the sow and her cubs probably were foraging on mushrooms when the attack occurred, the report said. 

While Mr. Crosby apparently was out for a short hike designed in part as exercise to recover from a sprained ankle and had a habit of traveling off-trail, he was not carrying bear spray as he walked through the mountain's mature lodgepole forest, noted the report. Wounds on his hands and an arm indicated he tried to fight back against the sow, the report said.

"... since there is evidence of natural feeding in the area, it is likely that the bears involved in the attack and consumption of Mr. Crosby were in the area feeding and/or bedding when Mr. Crosby entered the area. This brings up the possibility that the bears were surprised at close range by Mr. Crosby’s off-trail approach, although we have no way of knowing this for certain," added the report.

The grizzly sow was trapped the night after the attack and later put down, while her two cubs were shipped to a zoo.

"The primary reason these bears were removed from the wild is the killing and consumption of a human. The objective of removing the adult female grizzly bear and two cubs that were involved in the fatal attack and consumption of Mr. Crosby within hours of his death was to prevent these bears from killing and consuming another human in the future," the BOR report said. "Bears are an intelligent, highly adaptable species that quickly learn to exploit new food resources, especially foods that are easily obtained and contain concentrated sources of fat and protein. Since bears readily learn new foods and remember the locations, circumstances, and foods that are available, the possibility of these bears preying on people in the future could not be ruled out."