Jason Arunn Murugesu
BBC News, North East and Cumbria
Family handout
Jenny Hall was last seen leaving her home on Tuesday afternoon
The search for a missing woman has entered its fourth day, police have said.
Jenny Hall, 23, was last seen leaving her home at Barracks Farm, Tow Law, County Durham, on Tuesday just after 15:00 GMT. Her red Ford Focus was found parked on the B6278 between Eggleston and Stanhope on Wednesday.
Ms Hall, a keen long-distance runner, is described as 6ft (1.8m) tall with very long dark hair and was last seen wearing a blue hoodie with a John Deere logo and dark jogging bottoms.
Durham Police said it would be working in Hamsterley Forest, where Ms Hall was known to run, and the surrounding areas.
Hamsterley Forest was created by Forestry England in the 1920s.
Sections are used for lumber production, but the area is also popular with walkers and cyclists.
Spanning 4,942 acres (2,000ha), it is the largest woodland in County Durham and is located about 16 miles (26km) from the town Ms Hall is from.
It attracts about 200,000 visitors a year, according to Forestry England.
Ch Insp Haythornthwaite said he wanted to thank those who had contacted them with information so far.
"We really do appreciate your help and support," he said.
He said the force was aware that families would be walking around the forest recreationally today and asked them to give space to officers conducting the search.
"Try not to disrupt the search area," he said.
The search is now focused on the running trails Ms Hall frequently uses
Alongside the police, Teesdale and Weardale Search and Mountain Rescue Team (TWSMRT) said its teams had so far searched over 60 miles (96.5km) of paths and tracks in Hamsterley Forest.
"The biggest challenge is the area size itself and the terrain," said volunteer Peter Bell. "The terrain is muddy and boggy."
A spokesperson for TWSMRT previously thanked the public for offers of help, but individuals were advised not to try and assist as it could "hamper the systematic search".
TWSMRT
Mountain rescue teams searched the moorland on Wednesday and Thursday
Motorbike officers, specialised sniffer dogs and air support drones have also been involved in the search so far.
Durham Police is urging anyone with any information to ring 999.