So when police this week publicly identified the woman whose skeletal remains were discovered in Belanglo State Forest in 2010 as Karlie Jade Pearce-Stevenson, Dr Hayes felt a sense of peace.

Now Karlie - and her daughter Khandalyce whose remains were mysteriously found near a suitcase in South Australia just three months ago – could finally return home to Alice Springs.

Dr Hayes - currently on an archaelogical dig on a remote Indonesian island - said the identification would also allow her to analyse her unique facial approximation technique.

‘’From what I saw (of Karlie’s photo) I think there are some aspects that worked well and others that could have been done differently,’’ she said.

‘’… But although the identification of ‘Angel’ is going to be very helpful at an academic level, the most helpful thing is that Karlie and her little daughter will finally get to go home.’’

A year to the day after Karlie’s remains were found, Dr Hayes had stood in the Glebe morgue with the young woman’s skull in her hands.

Unable to discover her identify through traditional methods, police had turned to Dr Hayes to give a face to the woman they had dubbed ‘Angel’ – due to the word ‘Angelic’ found on her T-shirt.

Dr Hayes painstakingly built up the layers of flesh, muscle and then skin using computer imaging techniques and CT scans. It was a technique she had used many times – but this time it was different.

‘’All cases stand out, and all skulls are unique. But Karlie is more special than most because she died such a short time ago,’’ she said. 

‘’Most of my research is with people who have only very distant relatives living today - or absolutely none at all.’’ 

This has included working with historical remains from a few hundred years ago, to putting a face to an 18,000 year old ancient species of hominid discovered in 2003 known as the ‘Hobbit’.

‘’Working with Karlie in 2011 meant many things to me, both personally and professionally, and she still does,’’ Dr Hayes said.

‘’When the NSW police requested my assistance this meant that my research findings would actually have the potential to be of help to Australian people.

‘’Working with Karlie also meant that I would be putting my research right on the line … it is only with forensic cases that I can see how effective my methods actually are.

‘’Working with historical, archaeological and palaeontological remains … I have no way of knowing how accurate the results are.’’

A key suspect in the killings of Karlie Pearce-Stevenson and her young daughter Khandalyce is in custody for committing child sex offences.

As police narrow in on those responsible for the brutal murders, it has been revealed that the main suspect is already in a NSW prison.

Fairfax Media understands he is behind bars after committing violent sex-related offences against children.

Homicide detectives investigating the double murder of the Alice Springs mother and daughter confirmed on Friday that they were following "a very strong line of inquiry" in relation to the case. 

Detective say they are "hopeful" of an early arrest, after raiding homes in South Australia and the ACT.

Police are now almost certain the single mother was murdered in or near Belanglo State Forest, south of Sydney, but are yet to determine the year of her death. They do not know whether her young daughter Khandalyce Pearce – whose body was discovered alongside the Karoonda Highway, in South Australia, in July – was also murdered in the same location.

Head of the homicide squad Detective Superintendent Mick Willing described the investigation as " fast-paced" and "complex" on Friday. He said the raids over the past two days had been "productive". 

Police are exploring the possibility that more than one person was connected to the murders of Ms Pearce-Stevenson and Khandalyce, who was aged between two and four. 

Police are confident that those responsible for the murders are not from Ms Pearce-Stevenson's home town of Alice Springs. She is more likely to have met or befriended the killer or killers while travelling between 2006 and 2010, police say.

More than one prisoner in NSW is considered to be a person of interest. It is understood that some of those prisoners are currently serving time for violent crimes committed in NSW. 

The homes searched in South Australia and the ACT are believed to belong to people associated with the unconfirmed sighting of Ms Pearce-Stevenson and Khandalyce at an ACT shopping centre in December 2008.

None of the homes are associated with the prison suspects.

"There is every indication that friends or associates – people Karlie may have met or been in contact with while travelling between 2006 and 2010 – hold the key to their deaths," Superintendent Willing said.

Police are yet to locate the car driven by Ms Pearce-Stevenson after she left the Northern Territory, between 2006 and 2008, but said it was a 1986 red or maroon Commodore VL station wagon. 

The car was initially registered to the young mother in the Northern Territory but had since been sold and re-registered in NSW to a person not connected with police inquires. Police have questioned a person who was connected with the car prior to it being re-registered in NSW. 

"We want to charge those responsible and ensure a conviction for what can only be described as the brutal murder of a young mum and her little girl," Superintendent Willing said.

- Ava Benny-Morrison, Lisa Visentin and Nick Ralston