District police are looking for a missing 88-year-old man who suffers from dementia and might have gone without medication for more than a week.

Family members last saw John Matthews when he went for a walk the evening of Dec. 10, according to Lt. Bobby Ladson, who heads the Metropolitan Police Department's missing persons division.

Matthews' wife told police that her husband frequently takes walks down 16th Street NW to the Carter Barron Amphitheatre in Rock Creek Park. But on that night, he never returned home, Ladson said.

Police have conducted two searches in the area near the theater but have not found Matthews.

"We're looking into everything we possibly could in terms of why he might be gone," Ladson said. "His family is very concerned because he has dementia, I guess in the full-blown stages of dementia."

Matthews left that night without a heavy coat, and police also are concerned that he has been outside during a few cold nights.

Matthews was last seen on the 1400 block of Oglethorpe Street NW, wearing brown pants, a blue sweater and a maroon vest. Police described him as 5 feet 9 inches tall, 155 pounds, with brown eyes, grey hair and a medium complexion.

He has a distinctive dark birthmark under his left eye.

Anyone with information about Matthews' whereabouts is asked to call police at 202-727-9099 or 202-576-6768. Those wishing to remain anonymous can text 50411.