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LANCASTER-- A Silver Alert has been issued for a missing man in Lancaster.

Police are searching for William Francis Johnston. He was last seen late Monday night walking on Roan Drive.

Johnston is 5'10' and weighs 260 pounds. He has grey hair and green eyes. He was last seen wearing a white shirt and green swim trunks.

Police say he has a cognitive impairment and they're concerned for his safety.

If you see him, call Lancaster police.

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