A forensic expert has revealed he will begin his own search for Nicola Bulley in "deposition sites" near the river where she went missing.
Peter Faulding led a private underwater search team as he joined the search for the mum-of-two last week, but left the village after three days of scouring several miles of the river.
Previously, the diver said his team's sonar could find Nicola in under an hour if she is in the river - however, he expressed doubts she ever fell in.
He has now launched his own "low-key" search and reportedly spoken to Ms Bulley's family about "deposition sites" - a term referring to a place where someone has been buried.
Mr Faulding told the Express: "I’m talking to the family and obviously have vast experience finding buried bodies. We’ve got to consider all options here, there has been that report of suspicious people hanging around.
"I was frank with Paul and Heather the other day because we need to consider possible deposition sites, we don’t know. I’m not saying the police aren’t doing that and what I don’t want to do is interfere with the police operation.
"Mine (investigation) will be low key, I will just be looking around for possible deposition sites."
Police are continuing trawl the River Wyre towards the sea at Morecambe Bay, working on one hypothesis that Ms Bulley could have fallen in.
Mr Faulding told the Daily Mail: "I think the worst mistake the police have made was to declare early on that she’s in the river rather than saying 'let’s keep lines of enquiry open'. This is a lady who knew this area intimately, she was slim and fit, and if she had fallen she could have grabbed on to the bank."
Ms Bulley vanished on January 27 while walking her springer spaniel Willow in St Michael's on Wyre in Lancashire, shortly after dropping her daughters, aged six and nine, at school.
Yesterday, the mum's friends and family showed she has not been forgotten by leaving yellow ribbons with handwritten messages on a bridge close to where she disappeared.
Ribbons with messages including "We need you home Nicola", "praying for your safe return" and "I love you" have been tied to a footbridge over the River Wyre.
A large poster with a photograph of Ms Bulley has also been attached to the railings.
It comes as the search for Ms Bulley, 45, a mortgage adviser from Inskip, has entered the 18th day.
So far, the police search has been aided by specialists and divers from HM Coastguard, mountain rescue and Lancashire Fire and Rescue Service, with sniffer dogs, drones and police helicopters.
Ms Bulley's partner, Paul Ansell, said he wants to keep "all options open" about her disappearance, but his "gut instinct" tells him she is not in the river.
He described Ms Bulley as "fun", "loving", "the most loyal friend you could ever have" and an "exceptional mum" who "absolutely adores our girls".
