PORTOLA VALLEY, Calif. (KGO) -- It has been more than 24 hours since a 79-year-old Redwood City woman with Alzheimer's went missing while hiking in Portola Valley.
Crews from across San Mateo County and the Bay Area have been searching for Margaret Elaine McKinley at the Windy Hill Open Space Preserve ever since.
More than 100 specialized volunteers have been combing the area where McKinley was last seen: along the Lost Trail near Skyline Boulevard.
A silver alert has been issued and, heading into the second night, crews are planning on expanding their search area to neighboring areas in an attempt to bring McKinley home to her family.
"I can't sleep. I can't eat. I cry all the time because I just keep thinking about what it would be like for her," said McKinley's partner, Kit Durgin.
Emotions ran high for Durgin as search efforts continued for her partner of 34 years.
McKinley went missing during a hike celebrating Durgin's 81st birthday. McKinley has Alzheimer's and is nearly 80 years old herself.
Durgin said it's common for McKinley to go ahead during hikes, but when she did Thursday while hiking along the Lost Trail, she got lost herself.
"We were out there celebrating that we could still hike, and we were enjoying the wildflowers and everything," Durgin said. "And at about three-and-a-half miles, Elaine just took off like an Energizer Bunny."
Search and rescue teams were on the trails quickly after and have covered a 14-mile area through Friday.
San Mateo County Sheriff Christina Corpus said more than 100 volunteers and specialized equipment are aiding the search.
"Our San Mateo County rescue units, our Bay Area mountain rescue units, and we have volunteers on horseback," Corpus said. "We have our sheriff's tracking and trailing K-9 unit, our bloodhound, and we have other K-9s that have been searching for Elaine as well."
San Mateo Co. sheriff gives update on missing 79-year-old hiker
High above the ground search, air support is using thermal scanners to detect any body heat along the search area as well.
These trails are challenging terrain, and crews will expand the search area in case she has gone further than expected -- all in the hopes to bring Elaine McKinley home.
"We will continue to be focused on finding Elaine and returning her to her family," Corpus said.
"To see the number of people who are so concerned and committed, it's overwhelming," Durgin said.
On Friday evening we saw search crews on horseback and on foot.
We spoke with residents who live in the area.
Andrew Naclerio and Samuel Kay visit this preserve weekly.
"It's super sad. It's heartbreaking. Any time somebody who has any kind of mental health problems. Like, I've heard dementia, that's a really tough, tough hand," Naclerio said.
He described the 14-mile terrain search and rescue crews have to scour.
"First of all, we're starting down here in the valley PV, and it goes all the way up to Skyline Boulevard, so it's a very three-dimensional preserve like a lot of hills," Naclerio said.
Both of Naclerio and Kay came out on Friday to help with the search.
"Kind of looking down a lot, trying to think like a dementia person or like an older person. Where would they go? And look into holes but, yeah, no luck," Kay said.
The sheriff's office told us foot patrols are winding down overnight, but efforts will ramp up Saturday morning.
Over 115 additional trained volunteers will be here, including one team from San Joaquin County.
Trails in the area are open to public use, but the Sheriff's Office is asking people to avoid disrupting search teams.
Authorities are asking anyone who sees Margaret "Elaine" McKinley to call 911. She was last seen wearing a red jacket and black pants.