The family of a missing elderly woman suffering from Alzheimer's warned the Bribie Island retirement village from where she disappeared of her tendency to wander off.

But Marian Wallace's family believes the 71-year-old may have been missing for two hours before staff realised she was gone.

The search continues for Mrs Wallace, who was last seen about 3pm leaving the Embracia Retirement Village in Bongaree.

Police officers, water police, sniffer dogs, SES crews and volunteers have spent the last two days looking for Mrs Wallace.

The Brisbane-based helicopter Polair2 has also been called in to search thick bushland using heat-seeking technology.

Her daughter Sue Harrison said Mrs Wallace only moved into the retirement village's dementia ward on Thursday.

Ms Harrison said Mrs Wallace was living independently on the island with her two dogs previously. However the family made the decision to move her to Embracia when her Alzheimer's worsened.

"In the last month she'd started locking herself out of the house or locking herself in. She started walking the dogs at night and doing unsafe things like that," Ms Harrison said.

"When I [took] her to Embracia on Thursday afternoon I explained that she is not safe to be by herself ... if you don't watch her like a hawk, she'll get out."

Ms Harrison said Mrs Wallace had difficulty walking because of an injured hip, but added that she was "pretty tough" and "very fit".

"A lot of people - when you first meet her - may not be aware that she has Alzheimer's. It's only when you ask her more things you realise something isn't right," she said.

Mrs Wallace was last seen leaving the Bongaree facility on Goodwin Drive, walking up Sunderland Drive towards the Banksia Beach and Pacific Harbour area.

The 71-year-old is described as being 165 centimetres tall, with a small build and grey hair. She was wearing a green cardigan, light blue jeans, black shoes and was possibly carrying a hand bag.

Police do not believe Mrs Wallace took a bus or taxi off the island, but cannot rule out the possibility that she may have left. They believe she would have been in "a confused state".

Police have asked drivers with in-car cameras, who were heading along Sunderland Drive between 3-5pm on Sunday, to check whether Ms Wallace was captured in any footage.

"Given the inclement weather over the past couple of days, Marian's age and her mental condition we do have real fears and concerns for her safety. But we're very hopeful by the same token," Bribie Island Sergeant Jimmie Driver said.

Embracia chief executive Wally Bourdelov said it was "very rare" for residents to disappear from the retirement village.

He said it was inappropriate to comment on the circumstances of Mrs Wallace's disappearance while the police search was under way.

"We do take the welfare and safety of our citizens seriously. The moment we found the resident missing we notified the family," Mr Bourdelov said.

"Places like ours are a resident's home, it's not a prison. It is their home and we try and make it as homely and caring for them."

Anyone with information should contact Bribie Island Police on 3410 9222 or Crime Stoppers on 1800 333 000.

Final searches of Bribie Island for missing elderly woman

Police divers are today searching the canals and estuaries on Bribie Island in the hope of finding clues to the disappearance of Marian Wallace.

The 71-year-old has been missing since Sunday and so far there are no clues as to where she may be.

SES crews and police are today scouring bushland on quad bikes and on foot.

The whole of the Island will have been searched by the end of the day.

Sergeant Ryan Hanlon says authorities at this stage believe Ms Wallace just "wandered off" however an extensive police investigation is underway in conjunction with search efforts.

MISSING person Marian Wallace had only been at Embracia nursing facility, Bribie Island, for a few days before going missing on Sunday.

Police and her family now hold grave fears for Ms Wallace, a “severe dementia” sufferer.

Police are concentrating their efforts on finding the woman and are not yet speculating on how she disappeared from the nursing facility.

Embracia chief executive officer Wally Bourdelov said in a statement they were “assisting police” in the matter.

“On Sunday, as soon as her absence was identified, staff immediately followed mandated protocols, notifying the authorities and initiating a search of the building and surrounding area.”

Bribie Island police officer-in-charge David Crawford-Raby said that was their last confirmed sighting was made about 8.30am Monday near the Bribie Island arts centre at Sunderland Drive, nearly 3km from her home at the Goodwin Drive facility.

“We are extremely concerned for her welfare,” Acting Inspector Crawford-Raby said.

He maintained police were still in a rescue phase of the investigation.

“This is still firmly a rescue operation, we are continuing to revisit the tracks and bush land around Sunderland Drive.”

When last seen, Ms Wallace had been wearing an aqua jacket and carrying a black bag.

The 71-year-old, known as “Mim” or “Mimmie”, had been concerned about the move and was distressed to leave her two dogs behind, according to her family.

Stepdaughter Sue Harrison, Ms Wallace’s main carer before the move, said her mother was a strong and wiry woman, who loved the bush and animals.

Police are still conducting extensive searches of Bribie Island and have focused most of their efforts on Bellara and Banksia Beach.

Sergeant Jimmy Driver, coordinating the search at the arts centre, said water police, volunteer marine rescue, SES and community members had been assisting.

“We’ve got to leave no stone unturned, we’ve got to retrace every step. The canals have been comprehensively searched top to bottom ... all around Banksia Beach and Bellara.”

Police divers have also searched the Pumicestone Passage and police have monitored the bridge camera.

They have found no trace that she has left the island.

Police want to hear from anyone who has seen Ms Wallace or may have given her a lift.

They say she may appear confused, or completely lucid.

“If they could please ring police immediately, or contact Crime Stoppers,” Acting Inspector Crawford-Raby said.

Daughters Ms Harrison and Sian Jamison said their mother had a number of grandchildren missing their “Mimmie”.

“Mimmie, come on home,” Ms Harrison said.

SUE Harrison is desperately calling for anyone to help her family find her mother, Marian Wallace.

Sue is one of Marian's five daughters, who are all distraught about the disappearance of the 71-year-old woman who is suffering from Alzheimer's disease.

Marian had been living in Embracia On Bribie for only a short time when she left the nursing home on September 7. She has not been found since.

Sue said with Alzheimer's disease, Marian could have left for a range of reasons.

"Anything is possible. If you know anything about that horrible disease, it would depend on the moment," she said.

"She was talking to the staff about Wamuran, which is where she used to live, and she was talking about a hospital appointment."

Marian has a large family and is a grandmother to seven and a great- grandmother to five children, all of whom have come together in this difficult time.

"We're keeping as busy as we can, focusing on getting her back, but needless to say, we're all pretty distraught," Sue said.

Sue said they think Marian may have been given a lift off the island.

"When you're first talking to her, you may not pick up that she has dementia," she said. "We understand if someone has given her a helping hand. We just need any information to help us."

Bribie Island officer-in-charge Acting Senior Sergeant Ryan Hanlon said the search was still going on all over Bribie Island.

"The search will continue until further information comes to hand or Marian is located," he said.

Acting Snr Sgt Hanlon said the community response to find Marian had been great.

MISSING

If you have any idea where Marion Wallace is, please call Bribie Island police station on 3410 9222 or Crime Stoppers on 1800 333 000.

Search continues for missing Bribie Island woman Marian Wallace

Kristian Silva - Brisbane Times

Final searches of Bribie Island for missing elderly woman

Bribie Island missing person Marian Wallace moved to Embracia nursing home days before going missing

Authorities still searching for missing Bribie Island woman Marion “Mimmie” Wallace, while new missing person’s case

Please help find mum: Marian Wallace's family plea

Search for Marian Wallace scaled back after a month missing