Julie Butcher, a friend of missing woman Gaynor Lord, said she received two calls from her on Friday afternoon, when she disappeared
Ms Butcher said she saw her friend in Jarrolds, the Norwich department store where Ms Lord worked, three days earlier, when she "seemed fine"
Police say there's a "high probability" that mother-of-three Ms Lord went into the River Wensum in the city
Officers say this "working hypothesis" is based on CCTV footage and their "very limited" witnesses - though say they're keeping an "open mind"
They've also released new video of the 55-year-old walking along St Augustine’s Street - which they say is the last footage of her before she went missing
Divers are searching the river for Ms Lord and continue to look through Wensum Park for clues
A member of the public found clothing and jewellery belonging to Ms Lord in the park on Friday
In his update to reporters, Ch Supt Dave Buckley said: "Nobody saw her go into the river but we know she ended up in the park"
When asked what makes him so convinced Gaynor Lord is in the water, Ch Supt Buckley replies: "Everything we know is pointing to a high probability that Gaynor went into the water."
He says that conclusion comes from CCTV and the "very limited witnesses" they have got available, along with details about her behaviour in the lead up to her disappearance.
Ch Supt Buckley says: "It's very challenging, the river is full of water due to all the rain.
"The divers can see about one-foot in front of them. It's extraordinarily challenging - so it's slow and methodical at the moment."
Ch Supt Dave Buckley says specialist teams from Lincolnshire are helping with the search and that sonar equipment is being put across the river.
This "quite detailed" approach allows divers to target where they think there might be objects.
Ch Supt Dave Buckley is asked for an update on the investigation so far and says "the focus is still very much on the river".
He says the working hypothesis remains that Gaynor Lord is in the river, but they are exploring other lines as well.
Image source, Shaun Whitmore/BBCNorfolk police are to hold a question and answer session, giving a fresh update on the search.
Ch Supt Dave Buckley will be answering the questions.
We will bring you more updates as soon as it begins.
Jo Black
East of England correspondent
The police underwater search unit has been set up in Wensum Park.
It has been closed since Saturday but journalists were allowed in the park, under guidance from the police, to get closer to the search operation.
On Friday, Gaynor Lord, 55, went missing after leaving her work on the Bullards Gin counter in the basement of Jarrolds department store, in Norwich.
The map below shows where she was spotted until her clothing and belongings were found at 20:00 GMT.
Ahead of the Norfolk Constabulary press conference at 14:00 GMT, police officers and journalists are gathering at Wensum Park in Norwich.
Image source, Shaun Whitmore/BBCJournalists preparing for police press conference
Image source, Shaun Whitmore/BBCJournalists gathering ahead of a press conference in Norwich
Press Association
A police tent has been erected at Wensum Park in Norwich as the search continues for Gaynor Lord.
A number of her belongings, including clothing, two rings, a mobile phone and glasses, were found scattered in the park.
Image source, PANorfolk police continue the search for Gaynor Lord
Image source, PAPolice were along the River Wensum
Maria Veronese
BBC Look East
I am just outside Wensum Park where I can see police re-entering the water.
Police are due to release more CCTV footage today - including of Gaynor Lord close to the park.
Norfolk police believe Ms Lord entered the water and will give more details at a press conference due to start at 14:00 GMT.
Image source, PASearch teams on the River Wensum
Gaynor Lord would have been "well familiar" with the area she went missing from, her tennis club's welfare officer has said.
Speaking to the EDP, external, Simon Valentine said Ms Lord was known to walk her dog along the river and her disappearance was "out of character".
Ms Lord regularly attended Wednesday morning sessions at Stanmore Tennis Club in Thorpe St Andrew until very recently, Mr Valentine added.
Police can be seen carrying bags from scrubland in Norwich.
Searches continue to find Gaynor Lord and Wensum Park remains closed to the public.
Police continue their search for Gaynor Lord
Officers were seen looking through the undergrowth
A search team continues its hunt
Norfolk Constabulary will provide an update on the ongoing search at 14:00 GMT.
Chf Supt Dave Buckley will brief journalists at Wensum Park.
Gaynor Lord's step-brother Allan Webster says her disappearance is "proper out of character".
In an article by The Sun, external newspaper, he said: "She has never gone missing or anything like that before.
"If anyone does know anything please come forward."
Image source, Shaun Whitmore/BBCRosie Richards believes she saw someone matching Gaynor Lord's description doing a "yoga pose" in Wensum Park
Earlier this week eyewitness Rosie Richards told the BBC she was walking in Wensum Park when she noticed a woman matching the description of Gaynor Lord.
She saw her take her coat off and "going into almost a meditative or yoga pose".
The pose looked like "she was going to lie on her front and arch her back."
She said it struck her as "slightly unusual" given the weather and temperature.
However, she said the woman appeared "calm".
Specialist divers are again searching the River Wensum which runs alongside Wensum Park.
A search team from Lancashire Fire and Rescue Service has also been seen 0.7 miles away (1.2 km) at New Mills Yard.
Image source, Shaun Whitmore/BBCDivers are spending a second day scouring the river
Image source, Shaun Whitmore/BBCNew Mills Yard is close to Norwich city centre
Jo Black
BBC News, East of England Correspondent
It is almost a week since Gaynor Lord disappeared and as the police searches continue at Wensum Park her family and friends can only wait for updates.
Public interest in the mother of three’s disappearance seems to be growing. Today at the park there is a notable increase in media outlets covering the story compared to the last few days. More journalists and camera operators can be seen pointing their lenses at the river which is being searched by specialist divers.
Passers-by and even a motorist stopped his car to talk and ask reporters if there are any updates.
A search team has also been seen looking through wasteland near some houses just across the road from Wensum Park.
It is at the park, a mile-and-a-half from the retail assistant’s workplace at Jarrolds department store that her clothes and personal possessions, including her phone, glasses and two rings, were found.
Yesterday police issued CCTV footage showing some of the last known movements of Ms Lord.
We see her leave work from the gin counter she’d been working at - the CCTV still shows her smiling but we still don’t know why she left work more than an hour before her shift was due to end.
She is then picked up on cameras on various roads in the city. She appears to be hurrying, walking quickly, sometimes jogging and even manoeuvres around moving traffic at a road crossing.
Police say she spent around 30 minutes in the cathedral grounds, they hope by releasing this footage it will jog someone’s memory and yield useful information to help their investigation.
Image source, Norfolk ConstabularyGaynor Lord pictured in a car
Norwich's policing commander, Supt Wes Hornigold, says detectives have been "linking in" with Lancashire Constabulary to try to understand "any of the lessons learned" from Nicola Bulley's disappearance.
Ms Bulley, 45, went missing in January after dropping her two daughters off at school in the Lancashire village of St Michael's on Wyre.
Image source, Family handoutHer mobile phone was found on a riverbank and her body was discovered in the river three weeks later.
Last month, the College of Policing published a report which criticised the media strategy during the search for Ms Bulley.
Police are keen to hear from anyone who may have seen Gaynor Lord on the grounds of Norwich Cathedral.
CCTV footage shows her going into the grounds of the cathedral at 14:50 GMT on Friday.
She is there for about half an hour before she is seen leaving at 15:23.
Supt Wes Hornigold said: "It's not clear where she goes inside the cathedral grounds during this time so we’re keen to hear from anyone who may have seen her there.
“We are continuing our extensive searches but would appeal to the public to come forward with any information which may help to find Gaynor."
Image source, Norfolk PoliceCCTV footage shows her going into the grounds of the cathedral at 14:50 GMT on Friday