BILLINGS - Wildlife agents were trying to capture a grizzly bear in Yellowstone National Park on Monday after it killed a Michigan hiker in the second fatal bear attack this summer at the famed park.

The body of John Wallace, 59, was discovered Friday in a backcountry area known for its high population of bears. An autopsy concluded he died from injuries sustained in a bear attack.

After a fatal mauling last month - the first inside the increasingly crowded park in 25 years - authorities let the responsible grizzly go because it was protecting its cubs.

This time, rangers have set traps with the intent to capture and kill the bruin that attacked Wallace. Its guilt would be established through DNA analysis connecting it to evidence found at the mauling scene, park officials said.

"We know of no witnesses to the attack," park superintendent Dan Wenk said Monday. "We're going to err on the safe side of caution since we'll never really know the circumstances in this case."

The bear that killed Wallace is believed to be a different animal than the one in the July killing.

The earlier mauling occurred about eight miles away from where Wallace's body was found. In that instance, a female bear with cubs attacked a couple from California, killing the man before fleeing.

There were no signs of cubs in the area where Wallace was killed.

Park spokesman Al Nash said the chances of trapping the killer bear are uncertain. A favorite food for some grizzlies, the nuts of whitebark pine trees, became available in the last several days. That typically draws bears to elevations higher than where Wallace was killed, Nash said.

Wallace had entered the park alone last Wednesday and pitched a tent in a developed campground, Wenk said.

Authorities said he likely was killed Wednesday or Thursday during a solo hike along the Mary Mountain Trail. The trail is closed from March to June because it passes through an area frequented by grizzlies feeding on the carcasses of bison that died over the winter, park officials said.

It is typically re-opened for public use on June 15, after the carcasses have been eaten, Nash said.

There are more than 600 bears in the greater Yellowstone area, and Chris Servheen, grizzly bear recovery coordinator for the U.S. Fish and Wildlife Service, said the Hayden Valley where Wallace was killed is known to have "a lot of bears."

Wallace's body was found along the trail in an area of open meadows interspersed with small stands of trees. He was about five miles from the nearest trailhead, where his vehicle was later located. Authorities said he was not carrying bear spray - mace-like canisters of compressed pepper spray used to defend against bear attacks.

A snack bar was found in his closed backpack, but authorities said it did not appear the grizzly tried to get at the food. Rangers also found numerous adult grizzly tracks and scat, or bear droppings, near Wallace's body.

A resident of Chassell, Mich., Wallace worked for about 20 years at the Portage Lake District Library in Houghton, a city in Michigan's western Upper Peninsula. He was married and had no children, said Shawn Leche, the library director.

Leche described Wallace as a quiet, easygoing man and conscientious worker who loved books, opera and the outdoors. He had asked for vacation time to camp and hike at Yellowstone, a park he had visited before, Leche said.

"It's hideously perverse to think that someone who loved nature so much would come to such an untimely end at the hand of nature," he said.

Two trails and a section of the Hayden Valley west of Yellowstone's Grand Loop Road remained closed to hikers. Hikers elsewhere in the park were asked to stay on trails, hike in groups of three or more and carry bear spray.

Once a rare sight even in the wilds of Yellowstone, grizzly bears have become an almost routine cause for curious tourists lining up along the park's roadsides for a glimpse. The bears are protected from hunting even outside the park under the Endangered Species Act.

Conflicts between humans and grizzlies have been slowly increasing in the Northern Rockies in recent years as the bear population recovered from near-extinction last century. Most interactions are relatively benign, such as raids on orchards or trash cans.

Yet Wallace's death was the fourth caused by grizzlies in the greater Yellowstone region in the last two years.

Despite the killings, officials said the rate of dangerous encounters in the park is extremely low given that more than 3 million people visit the park every year.

"We've averaged one encounter that has caused injuries a year for the past 25 years," Wenk said. "The record speaks for itself."

--

John Flesher contributed reporting from Traverse City, Mich.