DNA experts in the United States are providing NSW Police with new clues on some of the state's most baffling missing persons cases and unidentified human remains.

The cases include bones from at least two people found in sand dunes on Sydney's Kurnell peninsula in 2007 and remains located near Ballina on the north coast.

Unsolved homicide squad police believe the north coast bones, found at an undisclosed site, may be those of missing 31-year-old Lennox Head mother-of-two Bronwyn Joy Winfield, last seen at her home in 1993.

Scientists at Orchid Cellmark in Dallas, Texas, have spent the past two months examining 31 exhibits of bone and tissue specimens, and a further 15 saliva swabs taken from relatives of missing persons.

The samples were delivered to them by Detective Sergeant Damian Loone, of The Rocks station, who has spent the past 12 years investigating the disappearance and suspected murder of northern beaches woman Lynette Dawson.

The only possible clue about the fate of the 34-year-old Bayview mother, who went missing in January 1982, is a pale-pink cardigan found near a hole that was dug for a swimming pool on her property.

Detective Sergeant Loone took the cardigan to the US to try to match Mrs Dawson's DNA with a sample from one of her daughters.

The detective is expected to return to the US in the next month to reclaim the exhibits and DNA results, which will be screened against those from relatives of other missing persons.

Saliva swabs taken from Mrs Winfield's daughters will be compared with DNA from bone fragments found on the north coast amid renewed inquiries by police in the past three months.

Mrs Winfield, who a coronial inquest declared dead in 2002, was reported missing by her estranged husband 11 days after she was last seen at her home.

The US tests could also reveal the sex of at least two people from three separate sets of bone fragments found in dunes in 2007 during land clearing preparation for the construction of the Sydney desalination plant at Kurnell.

Hunt on 'until the day you die' for Lynette Dawson's killer

NSW Police said yesterday they would hunt the killer of Sydney mother Lynette Dawson "until the day you die".

They also offered a $100,000 reward for information that would lead to a conviction.

The mother of two, from Bayview, on the city's northern beaches, last spoke to her family on January 8, 1982, and was reported missing by husband Christopher Dawson a month later.

The case was initially filed as a missing persons report, but in 1997, Detective Sergeant Damian Loone began investigating Mr Dawson, a former rugby league player with the Newtown Jets in Sydney, whom he believed was responsible for the murder.

Mr Dawson, who now lives in Queensland, claims his wife is still alive. He told police she phoned him after her disappearance to say she needed "time away" from their marriage.

A 2003 inquest heard that at the time of his wife's disappearance, Mr Dawson -- then a high school PE teacher -- was having a sexual affair with one of his students, Joanne Curtis, 16. Mr Dawson married Ms Curtis two years after his wife's disappearance, but the pair divorced in 1994.

Ms Curtis told the 2003 inquest Mr Dawson took her to a hotel about two months before Ms Dawson's disappearance, and left her in the car while he went inside. "He came back and said to me, 'I went inside to get a hitman to kill Lyn but I decided I couldn't do it because innocent people would be killed'," she said.

Sergeant Loone yesterday appealed for the alleged hitman to contact police. "Someone out there knows what happened and I plead to their conscience to come forward," he said.

Mr Dawson did not attend either the 2001 or 2003 inquests.

Police Minister Michael Daley said detectives would continue to investigate. "They will not close this file. They will hunt you down until the day you die -- do the right thing, come forward now."

$100,000 reward offered for missing woman

THE NSW government has offered a $100,000 reward for information leading to a conviction for the presumed murder of a woman who has been missing for 28 years.

Lynette Dawson, a 33-year-old mother of two, was last seen in 1982.

Mrs Dawson spoke to her mother on the evening of January 8, 1982, while she was at home with her husband Christopher Dawson at Bayview on Sydney's northern beaches.

She made plans to lunch with her mother the following day at Northbridge Baths, but did not show up.

Detective-Sergeant Damian Loone said as a matter of conscience anyone with information should come forward and give the family closure.

Mrs Dawson's brother, Greg Sims, said the family still grieved for her loss.

"The girls (her daughters) have been denied their mother and their mother's love and we all need to know the truth of what happened to her," he told reporters today.

"We greatly appreciate this reward being offered and hope it will bring a person or persons forward who believe they know what happened to Lyn."

Closing in on the killers

VETERAN homicide investigators will tell you there is no such thing as an unsolved murder.

There are just murders for which there has not been enough evidence to prove who did it.

"Most detectives believe they know who the killer is, and there is an old adage, 'you end up speaking to the killer even though you may not know it within about 48 hours of the murder'," retired homicide detective Michael McGann said.

Mr McGann said every homicide cop had at least one case which sticks in their craw - one they could never prove, but knew who did it.

"Mine was a little five-year-old girl called Renee Aitkin," he said.

"Over a few beers my partner and I discussed the idea of grabbing him, tying him to tree, putting a gun down his throat and asking him what he did with Renee's body."

But sanity and reason prevailed instead of justice and Renee's murder is still considered unsolved.

Renee was five when she was abducted from her Narooma home on the South Coast in February, 1984. Her body has never been found and she is still listed by NSW police as a missing person.

"My partner and I knew who did it. We needed to find her body," Mr McGann said.

Fast forward to 2009 and the horrific mass murder of the five Lin family members is another example of detectives having a good idea of the killer but biding their time until the evidence is there to pounce.

A source within Strike Force Norburn, set up to investigate the brutal murder of Min and Lily Lin, their sons Henry and Terry and Mrs Lin's sister Irene, said detectives had always been confident they knew who was responsible for the killing on July 18 last year, but they had to be strategic.

"You only get one go, it's not something you rush for the sake of it," the police source said.

Similarly, officers working to solve the execution-style killing of North Shore businessman Michael McGurk have always been confident they knew who was behind his murder.

What makes it more difficult for homicide officers is when no body is ever found.

But every time human bones are found, there is a group of detectives - retired or still serving - who take a very keen interest in their discovery.

They are the cops who have an unsolved case on their books, and they hope the bones belong to "their" case'.

"When I hear about bones being found, my ears prick up," Detective-Sergeant Damien Loone said.

Thirteen years ago, Sgt Loone was handed the cold case file of missing Sydney mother Lynette Dawson, 34, who vanished from her Northern Beaches home on January 9, 1982. "At that stage it was a missing person's case, and was 15 years old then.

"Even after 28 years, you hope the bones turn up and provide the last pieces in the jigsaw," Sgt Loone said.

When trail bike riders stumbled across a human skeleton in the Belanglo State Forest last Sunday, cold case detectives across NSW braced for the possibility it could be the last piece of the puzzle and solve their case.

"You never know. Lynette's sibling's DNA is on a data base and if they believe these bones are of a female aged 30 to 40 it's a possibility," Sgt Loone said.

Frustration of not being able to get the killer leads to fantasies of breaking the case and creative "ways" of getting the evidence.

Another "bones" case still being investigated by police is the remains of a male and female unearthed by workmen clearing land for the desalination plant at Kurnell about three years ago.

A shin bone was found by the workers in October, 2007, and days later, about 300m away, ribs and other smaller bones were found in sandy scrubland off Sir Joseph Banks Drive.

Then, a pelvis and foot bones, eerily still wearing a sock, were found.

Forensic tests carried out revealed the bones belonged to two people who died less than 50 years ago.

Just as the bones in Belanglo raised the spectre of a new- found victim of Ivan Milat, the discovery at Kurnell had many speculating they could be the victims of convicted killer Arthur "Neddy" Smith.

Smith was known to favour the dunes south of Sydney as a dumping ground for murders he committed in the '70s and '80s of unwanted underworld associates. Rubbish found with some of the bones indicates they were probably from some time after the 1970s but tests offer no clue to whether the pair were murdered, died accidentally, or even died together.

In the dark for 28 years: search for truth of what happened to Lynette Dawson

Paul Tatnell - SMH
September 21, 2010

Lynette Dawson was 33 when she disappeared from Sydney's northern beaches in 1982, leaving behind two daughters.

Police have listed her husband - former Newtown Jets football player turned teacher, Chris Dawson - as a possible suspect.

Mr Dawson, now 62, has continually denied playing any part in his wife's disappearance despite a police investigation and evidence at a coroner's inquest that he was an abusive husband.

Today a $100,000 reward has been offered in a bid to get information that might lead to the 28-year-old mystery being solved.

Mrs Dawson's family told The Sun-Herald in 2003 that their first impressions of Mr Dawson were of a "gorgeous" and charming man.

Mrs Dawson's uncle Bob Simms told the newspaper that Mr Dawson "was like a film star".

"In fact he starred in a couple of television ads. He seemed to be a good style of a man back then, but I think it went to their heads, he and his [twin] brother [Paul]."

But, as time wore on, it became evident he was "a monster, a domineering control freak", one of Mrs Dawson's family members told the newspaper.

The details of Mr Dawson's treatment of women were revealed in a 2003 coroner's inquiry into Mrs Dawson's disappearance that led to deputy NSW coroner Carl Milovanovich recommending a "known person" be charged with Mrs Dawson's murder.

The inquest also revealed Mr Dawson, then a teacher at Cromer High School on Sydney's northern beaches, had sexual relationships with his students.

One affair was with Joanne Curtis, then a 16-year-old student who would later became his wife.

Ms Curtis later detailed for the coroner her husband's domineering behaviour.

According to evidence given by Ms Curtis, Mr Dawson was possessive, violent and unwilling even to let her out of the front door without his permission.

"He chose what I wore. If I was going somewhere, he would have to approve it," she said.

"He was violent. There were some times when I locked myself in one of the bedrooms and he would try to break the door down."

Ms Curtis also detailed how Mrs Dawson was treated by her husband.

"He was very cold and used to sing songs to her that had double meanings, that he didn't care about her and that she was physically unattractive," Ms Curtis said.

"Just digging away at her. Just singing songs that were to wear her down, just upset her."

Ms Curtis told the court she began babysitting for the Dawsons and eventually moved into their home.

She also claims that Mrs Dawson began to suspect the affair.

"Lyn confronted me ... and said to me, 'You've been taking liberties with my husband.' I didn't know what to say," Ms Curtis said.

The coroner heard that, some time in 1981, Mr Dawson spoke of killing Mrs Dawson after he drove Ms Curtis to a Sydney hotel. She waited in her school uniform in the car while he went upstairs.

"He wasn't there for long. When he came back he told me, 'I wanted to get a hit man to kill Lyn, but I couldn't do it because innocent people would be killed,'" she said.

But no criminal charges have ever been laid over Mrs Dawson's disappearance.

Police thought they had made a breakthrough earlier this year following the discovery of one of her cardigans with supposedly crucial DNA evidence. Mr Dawson said at the time that he was happy to provide his DNA to police.

Detective Sergeant Damian Loone told the 2003 inquest that he believed Mrs Dawson was murdered and her body disposed of between 9pm on Friday, January 8, and 8am on Saturday, January 9, 1982.

Mrs Dawson's brother, Greg Simms, today said the family still grieved for her loss.

"The girls [her daughters] have been denied their mother and their mother's love and we all need to know the truth of what happened to her," he told reporters today.

"We greatly appreciate this reward being offered and hope it will bring a person or persons forward who believe they know what happened to Lyn."

Anyone with information can phone Crime Stoppers on 1800 333 000.

- with AAP