Police say they are concerned for the welfare of a 62-year-old Aboriginal woman who hasn't been seen by family in Central Australia for more than three weeks.
When Beryl Collins was reported missing on April 4, police believed she had not been seen by family for five weeks.
After further investigations, police determined Ms Collins was last seen walking near the Albrecht and Larapinta Drive intersection between 6.30 and 7am on March 14.
Police said she had been at a house on Holtermann Court the night before where there had been a verbal argument involving members of her family.
Senior Sergeant Michael Potts said the argument had made Ms Collins upset.
Ms Collins was last seen wearing a grey-coloured skirt, a dark-coloured top and carrying a black backpack, which police believe was filled with groceries.
Senior Sergeant Potts said police were "gravely concerned" for Ms Collins' welfare because she has numerous underlying health conditions, some of which require medication.
He said Ms Collins may also have dementia.
"She may get confused (and) wander off into bushland," Senior Sergeant Potts said.
Search continuing
On Thursday morning, two police officers on motorbikes searched an 11-kilometre stretch of road from Alice Springs to the Simpsons Gap turn-off on Larapinta Drive.
Senior Sergeant Potts said the land search would be extended to the southern side of Larapinta Drive and into bushland over the next couple of days.
He said police would consider an air search as the investigation progressed.
Senior Sergeant Potts said police were considering numerous possibilities including that Ms Collins could have wandered into bushland or been picked up and taken to a remote community.
He said police had investigated reported sightings of Ms Collins in Alice Springs and determined that those sightings were actually of her sister.
"That's not to say that Beryl isn't still here in Alice Springs... that's one scenario we are looking at at the moment."
Police have urged members of the public to assist them with their search.