INVERNESS (KPIX) — Search teams returned to the hiking trails and thick underbrush of rural Marin County Tuesday, looking for any sign of a Palo Alto couple who have been missing since last week from a rental home in Inverness.

Aided by tracking dogs and helicopters with infrared cameras, 40 searchers spread out in the wooded area hoping to find a trace of Carol Kiparsky and Ian Irwin, who were last seen on Friday.

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A third elderly hiker, identified as 76-year-old Robert Bennett, was also reported missing in the area on Tuesday afternoon, according to the Marin County Sheriff. Teams searched for him all night and he was eventually found alive around 11:30 p.m. Tuesday.

“It’s a true mystery, very distressing but it’s more of a mystery at this point and we hope we find them,” said Felix Chamberland, who lives nearby and has taken part in the search for Kiparsky and Irwin.

Family members also arrived on Tuesday from outside the Bay Area and joined the search.

Kkiparsky is 77 and Irwin is 72. The search for the couple began Sunday after they missed an appointment and it was discovered they had failed to check out of their rental cottage.

“We found a bunch of personnel effects that would normally go with someone if they were going to leave on a hike,” said Marin County Sheriff Sgt. Brenton Schneider. “We found hiking gear still in the house. We found cell phones, food that was still there, laptops so, it’s definitely a mystery as to where they’ve gone.”

More than 160 trained trackers searched for the couple on Monday including a fixed wing Cessna, a CHP helicopter, drones, dogs and even a mule.

Schneider said that there though less than half of searchers participated on Tuesday, the effort was more focused and more technical.

“It’s incredibly dense brush and I have some of the best Mountain rescue teams in Northern California that got really beat up, you know, crawling on their belly’s going through it,” said Incident Command Search Manager Michael St. John.

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Official said there was no evidence of foul play and nothing suggesting they went for a hike.

St. John said the couple are reported to be in good health and didn’t attribute them going missing to elderly dementia.

“If it was an elderly dementia or something like that, it would be different. But these two people are doing very well, and it just doesn’t make a lot of sense,” he said.

The lack of any clues was what has folks so concerned. Chamberland said he saw the couple last week.

“I saw them walking down the road and they looked like they were moving along. They didn’t look like big hikers. They didn’t look like they’d be cross country trekking whatsoever,” said Chamberland. “I said Hello to them and they nodded and acknowledged me.”

David Herbst, who lives in Inverness, has hiked the trails for nearly 20 years and says it’s not hard to become disoriented.

“I’ve been off trail a couple of times looking for something and realized, wait a minute, what is my point of reference?” Herbst said. “For example, if the sun’s not out, you can sometimes get totally turned around.”

The Marin County Sheriff said the last time Bennett was seen was around 1:22 p.m. on Monday. He was walking toward Valley Stone Trail Head. He’s described as 5 feet 10 inches tall, 150 pounds with gray hair and brown eyes. He was last seen wearing a gray flannel shirt and blue jeans, the sheriff’s office said on Twitter.

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