The head of an underwater search team brought in to help look for Nicola Bulley says the case is the most 'baffling' he has ever worked on.
Nicola, 45, vanished on January 27 from St Michael's on Wyre, Lancashire, after dropping her two daughters off at school.
The private underwater search experts used specialist equipment to look for Ms Bulley in the river, but their sonars did not find anything in the river on Monday, February 6, reports the Daily Mirror.
Peter Faulding, the head of the private diving team Specialist Group International (SGI), said his team of experts and divers, based in Dorking, Surrey, worked with Lancashire Police and hunted through "three or four miles" of the river until darkness fell.
"It's a negative search, no signs of Nicola," he said.
He said his team will look through another stretch of river on Tuesday "towards where Nicola originally went missing".
Speaking on TalkTV, Mr Faulding said he is "baffled" that Nicola has not been found after 10 days of searching.
He said: "After 25 years of doing this kind of work, after hundreds of cases, I am well and truly baffled. Normally you would expect the divers to find them easily.
"When people drown they generally go down where they are. We normally find them within five to ten days of where they went down.
"This is the most baffling case that I have ever worked on."
Nicola's partner, Paul Ansell, issued an appeal through Lancashire Police, saying her daughters miss her and need her back.
Mr Ansell said: "It's been 10 days now since Nicola went missing and I have two little girls who miss their mummy desperately and who need her back."
He added: "This has been such a tough time for the girls especially but also for me and all of Nicola's family and friends, as well as the wider community and I want to thank them for their love and support.
"We are also really grateful to Peter and his team from SGI for coming up and helping support the work of Lancashire Police as they continue their investigation.
"If anyone has any information which could help find Nicola, I urge them to get in touch with the police and help us provide the answers we all so badly need."
Detective Superintendent Rebecca Smith, of Lancashire Police, said: "The team working on this investigation are completely dedicated and determined to find Nicola.
"As a mother myself, I can't even begin to imagine what her two children are going through.
"Please be reassured that our sole focus is Nicola and that we are doing everything we can to find her.
"It is not possible to provide every piece of information to the public because to do so would detract from the investigation, but I'd like to thank everyone who has assisted us so far and for the support provided to Nicola's family at this extremely difficult time.
"They are being supported and updated throughout."
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