Someone pretended to be Karlie Pearce Stevenson for years after her death.

Suspects assumed murder victim’s identity so her family believed she was still alive.

At least three people suspected of being involved in the murder of Karlie Pearce Stevenson, 20, and her daughter Khandalyce Pearce assumed her identity to make it appear as though she was still alive, police believe.

They used the single mother’s bank account on hundreds of occasions in four different states since she was last seen alive in late 2008, accessing $90,000 before the account was closed earlier this year, the ABC reports.

Ms Pearce Stevenson’s remains were found at NSW’s notorious Belanglo State Forest in 2010.

Her daughter’s remains were found in a dumped suitcase beside a South Australian highway in July.

But the shocking double murders were only connected by a DNA match in recent weeks, since which time the mystery murder case has gripped the nation and police have made significant headway.

At a press conference in Adelaide this afternoon, Detective Superintendent Des Bray revealed the offenders used Ms Pearce Stevenson’s mobile phone to text family members as “some proof of life”.

“People we believe may be the offenders and others have taken over Karlie’s identity, her telephone, her bank accounts, her Centrelink and family payments,” he said.

“We need to determine if the people involved in the frauds are involved in the murder and it is most likely that one or more may be involved in some way.

He said at least one of the suspects involved in the frauds was a male and there were at least two females involved – all of whom lived at, or were connected to, properties in Canberra.

One of the women posed as Ms Pearce Stevenson, even producing identity papers, when she attended an Adelaide Centrelink office on December 15, 2010.

Detective Superintendent Bray said the suspects occasionally used Ms Pearce Stevenson’s mobile phone to access the message bank and contact her family members until mid-2011 to mislead people into believing she was alive and well, Fairfax Media reports.

“We know tragically that some of those SMSs were sent to family members to suggest that Karlie was still alive,” Superintendent Bray said.

He said a female pretended to be Ms Pearce-Stevenson while communicating with family and friends and persuaded a family member to transfer money into her account, which the offenders then withdrew.

Police believe the mother and daughter, last seen in Canberra, were killed at different times and in different locations.