Mystery surrounds the disappearance of a vulnerable woman after it emerged there is "no record" of her since her last sighting in 1999.

Margaret Fleming, 36, was reported missing by her two carers at her home near Inverkip, Inverclyde, on Friday, October 28, but there has been no independent sightings of her since a family party in December 1999.

Officers have been carrying out a major search since her disappearance but have so far drawn a blank and she remains missing.

A search of her house on Main Road has extended into the garden, which will be dug up by officers in the search for any clues.

Detectives from the major investigations team have now joined the probe, although it remains a missing persons case.

Police revealed last month it was an "unusual missing persons case" and Ms Fleming had a "side of her life" which she kept private.

Her home has now been searched and evidence bags removed. The garden and area surrounding the property has also been examined by officers.

STV News understands Inverclyde Council have no record of Ms Fleming since 1999 and there has been no social work or council involvement with her.

The council and the Department for Work and Pensions (DWP) declined to comment on the case but detectives say she has had no contact with local services or any other agencies.

Detective chief inspector Paul Livingstone said: "Apart from her carers, the last independent sighting of Margaret was in 1999.

"This, along with facts such as having no trace of a job, few friends that are contactable and no evidence of her contact with partner agencies and local services, has led me to become very concerned for her whereabouts and well-being.

"One line of inquiry that I now must consider is the possibility that Margaret may have come to some harm."

Specialist search teams have been sifting through the house where Ms Fleming is believed to live with her two carers to find any documentation, clothing and personal items that could assist in finding her.

Support from expert resources has been enlisted including air support, dive and marine unit, dog unit and search specialists, who have been combing the Inverkip and wider Inverclyde area.

Mr Livingstone added: "It's important that we keep an open mind to all lines of inquiry but the distinct lack of information about Margaret is concerning.

"However, we cannot rule anything out at this point and officers will continue to follow up enquiries about where Margaret has been. I must stress that this is still a missing person investigation.

"Our search will continue from the house into the grounds around it. This is a natural progression in the inquiry to assist our investigation to find Margaret."

Police have appealed for anyone with information to contact them.

Mr Livingstone said: "As this goes on, I am still appealing to anyone who may have information about Margaret to help us build a more accurate picture of where she has been and with whom she has been associating over the past 20 years.

"If anyone remembers Margaret from James Watt College in 1996, 1997 or 1998, whether a student or lecturer, please get in touch.

"We have spoken to a friend she met there but we are keen to find out if there is anyone else who may still be in touch with her."

He added: "Margaret's carers have said that they believe she has a private side to her life and that she may have friends that they are not aware of.

"We are currently working with very limited information which makes this a challenging investigation.

"If you know or knew Margaret, please get in touch with the investigation team based at Greenock on 101. Any small piece of information may be able to assist us."