Detectives say they are looking at 500 active pieces of information in the search for mother-of-two Nicola Bulley – and have not found “anything of note” yet.
Lancashire Police remain “fully open-minded” and have not yet detected a “suspicious element”, said Superintendent Sally Riley.
Speaking at a news conference on Tuesday, she said her officers had conducted an “unprecedented” number of inquiries.
Supt Riley also said the force had a team of up to 40 detectives working daily to comb through the “enormous” amount of information gathered so far.
This includes information from door-to-door inquiries, calls from the public, CCTV and dashcam, and data from Ms Bulley’s mobile phone and Fitbit device.
Police have also identified 700 vehicles that were in the area on the morning Ms Bulley disappeared and are in the process of contacting the drivers to request any dashcam footage they may have.
Supt Riley said Coastguard and mountain rescue teams were assisting in the search, while the UK’s National Crime Agency (NCA) were also helping the police with their inquiries.
“This is normal in a missing person inquiry and does not indicate that there is any suspicious element to this story,” Supt Riley said.
“The enquiry team remains fully open-minded to any information that may indicate where Nicola is or what happened to her.
“Any information that comes in that indicates otherwise is being checked out all the time and negated as each inquiry comes up.
“We are not closed in any way to any particular line of inquiry.”
Supt Riley added: “All of these extensive enquiries however have so far not found anything of note.”
Six specially trained officers are searching the River Wyre, near to the village of St Michael’s on Wyre, where Ms Bulley went missing on 27 January while walking her dog.
Detectives say their “main working hypothesis” is that the 45-year-old fell into the river and Supt Riley reiterated on Tuesday that this remained the force’s belief at this time.
But Ms Bulley’s family and friends have previously claimed there is “no evidence whatsoever” behind this.
Specialist teams, including a private company with underwater sonar equipment, are carrying out comprehensive searches over the river, but they are yet to find Ms Bulley.
Read: What were missing Nicola Bulley’s movements before she disappeared?
Earlier, a friend of Ms Bulley said it “may be time to start looking down other avenues” if search teams looking in the River Wyre cannot find her.
Family friend Heather Gibbons said: “I think it’s incredibly hard, but up to a certain level, we understand it’s human nature, it’s natural for everyone to have speculation, because the truth is in this, nothing is making sense.”
A dive team from Specialist Group International (SGI) joined the search for Ms Bulley on Monday, with a £55,000 side-scan sonar.
The team helped search part of the river on Monday, in an area around and downstream from a bench where Ms Bulley’s mobile phone was left, still connected to a work call.
Chief executive Peter Faulding said his team searched another stretch of the river, close to where detectives believe Ms Bulley fell in, on Tuesday, but said there were “no signs of Nicola”.
“We continue the search tomorrow,” he said in a post on Twitter.
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Speaking to Good Morning Britain, Mr Faulding said: “I personally think, if I rule this stretch of water out where we are working today, I don’t think she is here.
“I think there’s probably a third party involved.”
Police divers previously searched the same area last week as a huge hunt continued for mortgage adviser Ms Bulley, who lived in the village of Inskip, two miles from the river.
On Monday night, Ms Bulley’s partner Paul Ansell told Sky News she “has to be found safe and well” because “I can’t put those girls to bed again with no answers”.