MERLIN, Ore. -- Authorities were dropping supply kits into an area where they believe a San Francisco man is stranded in the snowy Oregon Coast range, hoping the food, supplies, and a heartfelt letter from his family will keep him alive until searchers find him.

James Kim, 35, has been missing for several days since he left on foot to try and find help for his family. Kim, his wife and two young daughters got stuck after driving along a snow-covered road near Grants Pass as they headed toward the Oregon Coast on vacation.

SKY 8

Helicopters fly over the search area.

Lt. Gregg Hastings, with Oregon State Police, said Wednesday morning that a total of 18 care packages would be dropped into an area they zeroed in on, after finding some of Kim's belongings as well as two "hot spots" where clues showed that Kim may have hunkered down sometime over the past four days.

Hastings said the letter written by the family would not be released to the media, but described it as a heartfelt plea from his loved ones, for Kim to hang in there until he is rescued. The letter was placed inside all 18 care packages.

Fresh searchers also joined the teams out in the snowy backcountry Wednesday morning, tracking a creek in a steep canyon where Kim's pants were found the day before.

His wife said that Kim was wearing the gray pants over jeans when he left the car on Saturday to get help.

"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."

Anderson said new crews would take part Wednesday and some who had searched earlier would return after a day's rest.

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

AP Photo

Josephine County Sheriff's office Sgt. Joel Heller speaks with members of a search and rescue team headed down Bear Camp Road in the Siskyou National Forest near Galice, Ore.

Kim went about two miles along the road then headed down into a drainage area, said Lt. Gregg Hastings of the Oregon State Police. The pants were found about a mile below where Kim left the road.

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

It could mean Kim suffered severe hypothermia, said Dr. Jon Jui, professor of emergency medicine at Oregon Health & 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 may belong to Kim.

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

Searchers pulled out of the lower canyon area Tuesday night because darkness heightened the risk. Anderson said searchers checked Black Bar Lodge, a popular summer spot along the Rogue that is closed in winter. They found no sign of him there.

AP Photo

A searcher and a tracking dog prepare to venture out to help look for James 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.

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

"He did have two lighters with him," Anderson said. "They survived nine days out there. They're pretty resourceful."

The Kims had been missing since Nov. 25, when they left Portland headed home after a holiday trip to the Pacific Northwest. They were to stay at a resort in Gold Beach.

On Monday, searchers in a helicopter hired by the family spotted Kati Kim, 30, and daughters Penelope, 4, and Sabine, 7 months. They were airlifted to Three Rivers Community Hospital in Grants Pass where Sabine was admitted. She was released on Tuesday. All three were described in good condition.

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  VIDEO: Helicopter hired by family locates mom, kids

  VIDEO: Kati Kim's parents call James Kim 'hero'

  VIDEO: Search update

  Family Web site

 CNET: Wife, kids of editor found alive

One searcher was injured Tuesday and airlifted out by Coast Guard helicopter.

After leaving Portland on Interstate-5, search leaders said, the couple missed a turnoff to Oregon 42 that leads to the coast and took a wrong turn on the twisty mountain Bear Camp 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 family told their rescuers that James Kim left his family about 7:45 a.m. Saturday in search of help and went the way they had come, saying he would return by 1 p.m. if he found none. He did not return.

Kati and James Kim.

Precipitation was forecast for Friday with temperatures expected to drop below freezing in the valleys and settle in the high 40s on ridges, which includes most of Bear Creek Road.

The 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 and can be impassable.

(AP also contributed to this article.)