HALLS CROSSROADS, Tenn. — It's been ten days since a 77-year-old Knox County man with dementia was separated from his family at the Halls Walmart.

Sheriff Tom Spangler said there have been no confirmed sightings of Jack Harrison in that time, but no one is giving up on the search.

Harrison was last seen about 9 p.m. Sunday, Nov. 17. Video from the store shows him at the Walmart gas pumps parking lot, heading toward Norris Freeway.

The Knox County Sheriff's Office said he suffers from dementia and other severe medical conditions that require medication.

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The sheriff is asking everyone living within a 10-12 mile radius of the Walmart to check their property and outbuildings, anywhere someone may have taken shelter. If you've already checked once, he asks that you do it again, because Harrison could still be on the move.

He also asks that anyone with surveillance cameras on the property to go back and check to see if Harrison might have passed by.

"We're asking people to be vigilant, keep your eyes open, and we'll continue to be looking," said Spangler.

The sheriff's office is checking out every possible sighting.

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He asks that if you think you see Harrison to please try to keep him in your sight while you contact authorities and until they arrive. His family has suggested telling him that "Karen is waiting for you" as a way to keep him nearby. 

Karen is his wife, and along with other family members, friends, and community volunteers, are continuing to look for Harrison.