Detectives fear that Laura Haworth was killed after she disappeared on January 5, 2008. Officers from ACT Policing and the NSW force have formed a joint task force to investigate the case.
The 23-year-old mother of two was last seen leaving a friend's house in Queanbeyan.
Police say they suspect "foul play" so they have launched a joint operation under the title "Strike Force Viking".
They are keen to know if the disappearance was or was not connected with anyone at the Summernats festival which was happening in Canberra at the time.
The element which has mystified them and the family ever since is that she had shown no indication of unhappiness. She had - and has - a loving family with two dependents whom she adored. Her children were 3 and 4 years old at the time.
Her bright red Mazda 121 sedan was found two weeks later on January 19, 2008, in Reid. Her phone and handbag were missing. There had been no activity relating to her phone or her bank account.
In January, her family made a heart-breaking plea for information on the anniversary of her disappearance.
"Laura is a mother, a daughter, a sister and a friend and we ache to know what has happened to her," they said.
Ms Haworth's Mazda was thoroughly examined but no details of what that examination might have revealed have been made public.
Having a personal vehicle from which to draw forensic "leads" is unusual among long-term missing persons, most of whom leave precious few exhibits, especially one the size of a car, to examine.
"Every day we live with what ifs, whys, and maybes. The pain of not knowing what has happened to Laura is brutal and has a huge impact on our daily lives.
"Laura we love you and miss you. You have a loving family waiting for news, please, please be in touch."
Previous public callouts have resulted in people coming forward with new pieces of information, Detective Senior Constable Shannon Pugsley said.
The detective from ACT Policing's Criminal Investigations Unit is hoping the Summernats weekend - where tens of thousands of car enthusiasts visit Canberra for the festival - will help spur new leads.
Around 12 months ago, Beth Cassilles was aware that a fresh piece of information on her daughter's disappearance had emerged.
"I know there's been some information shared with the police that seems important and I know that it hasn't been investigated yet because there's not the resources available to do it," she said.
"To me, that information is vital and it's like, 'wow, let's do it', but there's not the resources to do it."
Ms Cassilles's frustration with the investigation into her daughter's case bubbled over three years ago when she made an impassioned plea directly to Chief Minister Andrew Barr on ABC radio talkback.
She asked at that time for more police resources to help find her daughter. Mr Barr promised at the time to contact ACT Policing on her behalf.
Detective Superintendent Jamey Bellicanta said that as time goes on "the opportunity to seek additional information, be it forensic information or digital information, is reduced however, advances in technology have provided investigators with updated DNA and on occasions, personal information that have initiated further avenues of inquiry".
"Each individual investigation is undertaken by, for mine, passionate investigators and I want to stress to families of long-term missing persons that their loved ones are not forgotten," he said.
"But sadly in the mire of ongoing and contemporary investigations, on occasions we aren't placing the resources and effort that needs to be placed into these [missing persons] investigations."
Police and Ms Haworth's family have urged anyone with information about the Canberra woman's disappearance to contact Crime Stoppers on 1800 333 000.
