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David Mock, 88, of Fremont, has been missing since Thursday morning.

FREMONT -- Police need the public's help to locate a missing at-risk 88-year-old man who walked away from his home Thursday morning.

David Mock disappeared about 7:30 a.m. from his Margery Drive home near Fremont Boulevard, said police spokeswoman Geneva Bosques.

Mock, who police said has dementia and is hearing-impaired, was last seen wearing a white T-shirt, black lounge pants, brown slippers and a white handkerchief around his neck. He has gray hair, is 5 feet 2 inches tall and weighs 135 pounds. If contacted, he may say he is from San Mateo.

Anyone with information about Mock's location is asked to call Fremont Police Department at 510-790-6800 then press 3.

Contact Natalie Neysa Alund at 510-293-2469. Follow her at Twitter.com/nataliealund.