In a tweet, Tuesday night, the sheriff's office said crews are working to "extract" Bennett with the assistance of the Sonoma County Sheriff's Office.
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The Sheriff's Office says there is no update on his condition at this time.
The 76-year-old never returned from a Presidents' Day hike which prompted search and rescue crews to canvass trails near Big Rock Ridge in Marin County Open Space.
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Besides the help from a CHP helicopter, the sheriff's office brought out its drone, ATVs, and deployed 50 people on the ground, as well as five K9 teams, which picked up scents from Bennett's Jeep, which was parked down the street from the trail.
Stay with ABC7 News for the latest details on this developing story.