Karen Dalman, 59, was last seen on Tuesday in the Crystal Mountain area near Big Bear. Deputies say Dalman and a friend, 56-year-old Bruce Jackson, were on a day hike. They became separated after Jackson's pit bull got loose, and he went after it.
Jackson got lost himself and finally made his way back to his car on Thursday. He then drove home and alerted authorities. Jackson was treated for dehydration, but his hiking partner is still missing.
Dalman's son, Dan Nielsen, also joined the search effort, calling on his close friends to help out on dirt bikes.
A friend of Nielsen's spotted the missing dog, and an item belonging to Nielsen's mother.
"The dog started barking, and then they explored that option and went over there, and that's where the bucket with my mom's purse inside was, and it's kind of going from here," Nielsen said. "But it doesn't look like any of my mom's tracks were in the zone."
Nielsen says he questions why his mother was up in the mountains in the first place.
"My mom doesn't hike, I'll tell you that right now," he said.
Dalman is described as a white woman, about 5 feet 2 inches tall, weighing 125 pounds, with blond hair and hazel eyes. She was last seen wearing a light-colored top, tan capri pants and sneakers.
Forty searchers are being aided by a sheriff's helicopter in the investigation. Authorities say Dalman has no food or water, and there's added concern because she has a medical condition and has difficulty walking.
If you have any information about Dalman's whereabouts, you're urged to contact the Big Bear Sheriff's Station at (909) 866-0100.
The search for Dalman is expected to resume Saturday morning.