Police searching for Gaynor Lord have said they can't establish her state of mind with confidence as police teams search a river.
Ms Lord, 55, was last seen on Friday afternoon after she left work early from the Bullards Gin counter in the basement of Jarrolds department store in Norwich city centre.
The mother-of-three's belongings, which included a mobile phone, glasses, and two rings, were found scattered in Wensum Park - around 1.5 miles from her workplace.
Chief Superintendent Dave Buckley said: “There’s nothing we’ve been able to establish that really gives us a clear position on her state of mind that I would feel any degree of confidence of saying what we think it is at the moment.”
Officers said they are keeping an open mind, but that there was a "high probability" that Ms Lord entered a stretch of the River Wensum where specialist divers are now searching.
But the senior officer said: “Nobody’s seen her go into the river, nobody’s seen her go into the water. But we know she ended up in the park.”
Police earlier released CCTV footage of the 55-year-old walking along St Augustines Street at 4.01pm on Friday.
The 34-second clip shows Ms Lord wearing glasses and a long coat as she walks up the street, which is busy with passing traffic.
Mr Buckley said the CCTV footage they have collected did not reveal anything about the motivations for Ms Lord’s actions.
He said: “Some of this behaviour is out of character. We can’t explain some of her behaviour that day.
“We’re working really closely with family, with friends, with anybody else who might have had contact with her in the recent days or weeks to try and understand why this might have happened.”
Speaking to media at the scene, police said it will take "a couple of days" or longer to complete the search of the river.
"We're putting sonar equipment across the river, which is quite detailed in allowing us to try and target divers to where we think there might be objects," Mr Buckley said.
"But equally, it's very, very challenging. The river is very, very full of water with all the rain, full of lots of debris. The divers can see about one foot in front of them.
"So it's an extraordinarily challenging environment for them to work in so it's slow, methodical at the moment, working with equipment and it will take probably a couple of days to get to a position where we're kind of content with what we've done. It may even be longer."
Ms Lord is described as white, 5ft 6in, with blonde shoulder-length hair.
"There's nothing we've been able to establish that really gives us a clear position on her state of mind that I would feel any degree of confidence of saying what we think it is at the moment," he added.
"We continue to talk to friends, family, anybody who can help us that we know she's had contact with.
"We have got hold of her mobile device, we will work our way through that systematically... and see if we can find out more accurately why we've ended up where we have.
"It would be really premature I think if I offered too much suggestion as to what I think has happened."
In order to aid their search, Norfolk Police is attempting to learn lessons from Lancashire Constabulary, which handled the search for missing mother Nicola Bulley, who disappeared after dropping her two daughters at school in St Michael’s on Wyre, Lancashire, earlier this year.
