Fresh search teams joined the hunt Wednesday for a San Francisco man who set out on foot during the weekend to find help for his stranded family in Oregon's snowy coastal mountains.

Searchers tracking a creek in a steep canyon found a pair of gray pants on Tuesday that apparently belonged to James Kim, 35. His family said he was wearing them over a pair of jeans.

"This is frustrating. We are so close," Josephine County Undersheriff Brian Anderson said Tuesday evening. "There are people pouring their heart and soul into this. We are not going to quit until we find him."

Kim's wife and two daughters who were rescued Monday at their car, stuck in the snow on a remote road.

Heavy fog settled over the area during the night but was expected to burn off during the day Wednesday and searchers expected clear weather in the afternoon with temperatures in the 50s. The National Weather Service said overnight lows have been below the freezing point but no precipitation is expected until Friday.

Kim went about two miles along the road then headed down into a drainage area, said state police Lt. Gregg Hastings. The pants were found about a mile from where Kim left the road.

"It could be a sign he's trying to indicate the path he was going," Hastings said.

It also could mean Kim suffered severe hypothermia, said Dr. Jon Jui, professor of emergency medicine at Oregon Health and Science University. Jui said severe hypothermia causes people to become disoriented and have a false sense of warmth, which can lead to them disrobing.

"This is a bad sign," he said.

Anderson said searchers are trying to recover another item he did not identify that might belong to Kim.

Anderson said he does not know why Kim went into the drainage area. "I hope to have the opportunity to ask why he did that," he said.

About 100 rescue workers and four helicopters have been searching for Kim, following his footprints down a drainage called Big Windy Creek that leads to the Rogue River.

Kim, a senior editor for the technology media company CNET Networks Inc., had two lighters and was wearing tennis shoes, pants and a heavy coat, but no hat, Anderson said. He would likely be within about five miles of the car, he said.

The Kims had been missing since Nov. 25, when they left Portland and headed home after a holiday trip to the Pacific Northwest.

On Monday, searchers in a private helicopter hired by the family spotted Kati Kim, 30, and daughters Penelope, 4, and Sabine, 7 months. They were released from a hospital in Grants Pass on Tuesday.

After leaving Portland on Interstate 5, search leaders said, the couple missed a turnoff that leads to the coast and took a wrong turn on a twisty mountain road they chose as an alternative.

Stuck, they used their car heater until they ran out of gas then burned tires to stay warm and attract attention. With only a few jars of baby food and limited supplies, Kati Kim nursed her children.

The area's complicated road network is commonly used by whitewater rafters on the Rogue River or as a shortcut to the coast in the summer, but it is not plowed in the winter.