River searches are underway as part of the effort to locate 81-year-old Brian Warriss.
Mr Warriss went missing from his home in the village of Aldwark north of York yesterday afternoon (Sunday, 1 March).
North Yorkshire Police was again leading the search today.
A police search team and dog handlers are currently being supported by the Upper Wharfedale and Scarborough Ryedale Search and Rescue Teams and the York Rescue Boat in the search for Mr Warriss.
Officers continue to be concerned for his welfare and are appealing for information which would assist their enquiries.
They have also released CCTV video footage of him. It shows Mr Warriss walking along the road in Aldwark at around 4.45pm on Sunday.
He is wearing his distinctive bright red hat and fleece jacket, with navy trousers.
Neighbourhood Delivery Inspector Clare Crossan said:
Searches are currently ongoing to locate missing 81-year-old Brian Warriss.
We are covering a number of lines of enquiry and due to the last know sighting of Brian at his home in Aldwark and the proximity of the River Ure, York Rescue Boat are assisting us in carrying out searches on the river.
Anyone who has seen Brian, or knows of his whereabouts is asked to contact police on 101.
Please quote reference 12200036416 when contacting police.
Described by police as vulnerable, Mr Warriss is slim, has blue eyes and a grey moustache.
He was last seen wearing a red fleece, blue trousers and a red hat.