A grizzly bear that fatally mauled a hiker in Yellowstone National Park was killed after DNA evidence linked the animal to the scene of a second hiker's death a month later, a park official said Monday.
The decision to euthanize the 250-pound female bear was meant to protect park visitors and staff, Superintendent Dan Wenk said.
However, the investigation remains open, and officials might never know definitively whether the same bear that killed California hiker Brian Matayoshi on July 7 also took the life of John Wallace of Michigan in August.
Evidence showed multiple bears, including the sow, were near Wallace's body but not if the sow made any contact with Wallace. The bear was allowed to remain free after Matayoshi's death because park officials said it was reacting naturally to defend its two cubs.
"We made a decision at that time, based on all the information available, that we did not have a bear with a history or a bear that was demonstrating any predatory nature," park spokesman Al Nash said.
The deaths of Matayoshi and Wallace were the first blamed on a bear inside the park in a quarter-century. Two fatal maulings occurred just outside the park in 2010.
There were no witnesses to Wallace's killing. He was hiking alone in Yellowstone's Hayden Valley, about eight miles from where Matayoshi was killed. The mauling occurred in a backcountry area frequented by bears, and signs posted at trailheads warned visitors to take precautions.
By the time Wallace was found by other hikers a day after the mauling, one or more bears had fed upon his body, Nash said. Authorities couldn't determine from the evidence whether the sow bear "attacked Mr. Wallace or came upon the scene subsequent to the attack, but we certainly know the bear was at the scene," he said.
The sow bear was linked to the scene through DNA analysis of hair and scat samples found near Wallace's body, Nash said.
Park officials had observed the bear's movements through flights over the area in the weeks after the first mauling. The bear had been easy to locate because one of its cubs had a distinctive white patch that was visible from the air.
The two cubs were captured and relocated to the Grizzly and Wolf Discovery Center in West Yellowstone.
In the aftermath of Wallace's death, park officials said they did not believe the responsible grizzly was the same one that had killed Matayoshi because they found no cub tracks at the scene. Investigators now believe those tracks might have washed away in a rain storm that went through the area before Wallace's body was discovered.
Chris Servheen, a grizzly bear recovery coordinator with the U.S. Fish and Wildlife Service, said investigators have concluded the sow bear was at the scene for some time. He said details would be released when investigators complete their report into the attack, which is expected to take another month.
Servheen also said park officials had made the best decision they could after Matayoshi's death, given the circumstances.
"From everything we know, that was the right call," he said. "We don't know if this bear was involved in killing (Wallace), but it was there and it's a matter of trying to be careful."
Since the mauling, park officials have captured at least seven bears in the Hayden Valley. DNA, tracks and other evidence from the scene showed at least nine bears were present around the general time of Wallace's death, drawn by two nearby bison carcasses.
All of the captured bears were radio collared and released. Park officials said they will continue efforts to remove any bear that can be linked to the Wallace mauling scene and has a history of conflicts with humans.
Nash said those decisions would be made on a case-by-case basis.
An estimated 600 grizzlies live in the greater Yellowstone area, which includes parts of Wyoming, Montana and Wyoming. A recent report showed run-ins between humans and that growing bear population reached record levels last year, with 295 conflicts recorded by researchers.
Three of every four of those involved bears killing livestock or damaging property to get food, garbage, livestock feed or other human-related foods. Nine human injuries were reported in 2010 _ almost double the long-term average of five a year.
Since the attacks, Yellowstone has urged hikers to travel in groups of three or more, make noise on the trail and carry mace-like canisters of bear spray.
A record 3.6 million people visited Yellowstone last year.