Search dogs, using the scent they got from a piece of gear left behind by missing hiker T.J. Langley in the Glacier Peak Wilderness area, are among dozens of searchers looking for the veteran Seattle actor Saturday.

Langley, 42, failed to return Tuesday from what he told friends and family would be a two-day solo hike in the Okanogan-Wenatchee National Forest near Lake Wenatchee.

A helicopter, 40 searchers and the dogs are part of the search.

On Thursday, searchers found Langley's bivouac sack, a small cover pulled over a sleeping bag for extra insulation, on the trail up Buck Mountain.

That's good news, said Langley's sister, Joy Langley, because it meant he was on his way up the mountain and he'd completed two-thirds of his planned hike.

Joy Langley, speaking by phone from an airport on her way to Seattle, said she was told search dogs were able to get a good scent from the sack and are part of the search. She said the helicopter used heat-sensing devices when it flew over the search site, but no sign of him was found.

Searchers said they spoke to other hikers who said they saw Langley on the trail, but whether that was Tuesday or Wednesday wasn't clear. He had said he planned to be home Tuesday night, but his sister said the route he took was so rugged the family would not be surprised if he took another day to complete it.

He had told his friends where he was going and when he'd return, so it was easy to map a search area, his sister said, adding that there is no cell service on the mountain. Joy Langley said she's worried he may have fallen and broken an ankle so he couldn't hike out.

Langley, an avid outdoorsman and experienced backcountry hiker, checked in at a forest trailhead Sunday. His car, a 1970s Volkswagen Beetle, was found parked at the trailhead.

On Thursday morning, friends filed an overdue-hiker report, and the Chelan County Sheriff's Office initiated an extensive ground and air search.

Langley, who manages an apartment building on Capitol Hill, is also a veteran actor with a drama degree from the University of Washington. For more than a decade, he has been a member of Seattle's Repertory Actors Theatre, a nonprofit group known for staging shows with primarily multiethnic and nontraditional casts.

"He's a great actor, very natural," said Steven Ono, also a member of the theater group.

Ten years ago, Langley made news when he survived a grizzly attack while hiking in Yellowstone National Park. He said he had assumed he was going to die when he encountered the female bear.

He told a reporter he'd heard the pop when his pelvis was snapped and the crunch of jaws on his skull.

Recovering at home, his scalp a web of stitches, he vowed back then that his ordeal would not keep him from returning to the backcountry. And it didn't.

The Chelan County Sheriff's office, with assistance from the sheriff's offices in Snohomish and King counties and several volunteers, has been conducting the search, concentrating on the Clark and Buck Mountain areas.

Helicopters from Chelan and King counties searched from the air Thursday afternoon, and a fixed-wing Cessna conducted an aerial search midday Friday.

"The country we're looking at is steep, rugged, true wilderness area," Chelan County Deputy Sheriff Gene Ellis said. "Much of it is off-trail, meaning we're going through areas where there is no built-in trail."

Ellis said Langley apparently started his hike at Little Giant trailhead, a turnout on the Chiwawa River road about a half-mile past 19 Mile Campground in the Central Cascades.

E-mails have been circulating among the local theater community. Langley's friends believe that because he is an experienced hiker, he was most likely well-prepared for the outing. But night temperatures have been dropping, and Ellis said snow in low elevations has been forecast for Monday.