Eight-year-old Ian Bell who fell into the swollen River Wear five days ago is still missing, despite police checking 13 miles of water.
Ian was playing with friends when he fell into the Wear near his home in Sunnybrow, County Durham, on Friday night.
Specialists have been joined by members of the public in searching from the point he entered the water down to Durham City - a distance of 13 miles.
Specialist officers from Derbyshire Police with underwater cameras have joined colleagues from Durham Police, with assistance from County Durham and Darlington Fire and Rescue, Teesdale and Weardale Search and Rescue, the county council civil contingency unit and community volunteers.
Police will be at three bridges over the Wear to direct members of the public who want to help.
Chief Superintendent Andy Reddick, who is co-ordinating the operation, said: "The search for Ian will continue into its fifth day, but the hopes of finding Ian are fading.
"After four days of continuous searching using all resources we have available, we are still yet to locate him.
"During the search for Ian we have been overwhelmed by the offers of assistance from the local and wider community.
"Volunteers have been providing refreshments for our search teams and the general public. We would once again like to thank them for their help."