Nicola Bulley would not usually go near the river where she went missing, a forensic expert has claimed.
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 Wyre.
He has now launched his own "low-key" search and claims he has spoken to Ms Bulley's family about "deposition sites" - a term referring to a place where someone has been buried.
Today, the diver cast doubt over Lancashire Police's working theory that Ms Bulley could have slipped down a bank and fallen into the river.
Mr Faulding told TalkTV: "If Nicola slipped down the bank she would end up with water to the top of her legs, if she went out into the middle it's about 3.5m/4m deep.
"But the bench is quite a way back, so to actually get into the river you would have to be pushed very hard, or knocked out and shoved in the river.
"I mean the dog was dry here, so I don't believe that she's just slipped down the bank."
Ms Bulley would use her Fitbit to track daily walks with her dog, and then share the journeys on her Strava fitness app.
The forensic expert continued: "She was a very cautious lady and from talking to the family, she was a creature of habit.
"From Strava data, her family said she does not go near that river, she's really cautious. She takes the same route every morning, and this is what doesn't stack up.
"None of this stacks up at all."
Ms Bulley vanished on January 27 while walking her springer spaniel Willow, shortly after dropping her daughters, aged six and nine, at school.
Detectives have discounted foul play and are treating her disappearance as a missing person inquiry, working on the hypothesis that she fell into the river.
Today, officers were seen heading to a caravan site near to where Ms Bulley went missing, and are continuing to trawl the River Wyre towards the sea at Morecambe Bay.
The 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.
Yesterday, friends and family left 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.
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".
