Lincolnshire Police are looking to speak to dog walkers in the search for an 82-year-old missing man from Woodhall Spa.
Fred Gibson was last seen in the village at around 1.45pm on November 28 and police have been searching for him ever since.
He has been missing for two weeks and five days and police have now released CCTV of dog walkers who could have crucial information.
The people in the CCTV may have seen his vehicle, or Fred himself on the day he went missing.
Underwater search teams have been checking the River Witham, while officers have carried out house-to-house enquiries in the area.
Fred is white, 5 feet 10 inches tall with short hair and he was wearing a blue top and sleeveless shooting jacket when he went missing.
His Audi Q5 was parked at 3.15pm on the day he went missing close to the Railway Inn at Kirkstead Bridge.
Anyone with information has been urged to call 101 and quote incident 384 of November 28.