Authorities are asking for help finding a missing man in Mendocino County. The California Highway Patrol issued a Feather Alert for 36-year-old Samuel Sierra, last seen in Ukiah near South State Street and Observatory Avenue. Sierra is considered at risk and is described as 5 foot 7, 140 pounds, with black hair and brown eyes. If you spot him, call 911 immediately, and a photo is available on our website.