"It’s a huge coincidence." The serial killer theory that may explain the recent number of missing backpackers in NSW, & more in News in 5.

-With AAP.

1. “It’s a huge coincidence.” The serial killer theory that may explain the recent number of missing backpackers in NSW.

A leading forensic scientist believes the disappearances of three young backpackers in beachside towns on the NSW east coast could be the work of a serial killer.

Tim Watson-Munro believes police should not rule out a link between the disappearance of English backpacker Hugo Palmer, 20, Frenchman Erwan Ferrieux, 21, and missing Belgian Theo Hayez, 18.

“I don’t want to be hysterical about it but you have three foreign backpackers who have disappeared off the eastern seaboard of Australia, 300 kilometres apart, in very mysterious circumstances,” Watson-Munro told Channel 7’s The Latest on Wednesday.

“If you move the location from the coast to say, the New England highway, and you had three backpackers that were missing I think you’d have much greater cause for alarm.

“It’s a bit too cute to say they all drowned. It’s a huge coincidence if that’s the case.”

Friends Ferrieux and Palmer went missing from Shelly Beach near Port Macquarie on February 18.

They are believed to have drowned in rough surf, but their bodies were never recovered. Their rental car was found near the beach with their travel documents inside.

Last week, nearly five months after their disappearance, police said human bones found in the water at nearby Flynns Beach on June 15 and another two bones found in the water at nearby Flat Rock two days later were confirmed to belong to Ferrieux.

"DNA comparison of the three bones located in June have confirmed that they did come from the same male person,” Superintendent Paul Fehon told reporters in Port Macquarie on Monday.

"We believe from the DNA comparisons that it belongs to Erwan Ferrieux."

No trace of Palmer has been found.

Belgian Theo Hayez was last seen on May 31 more than 300 kilometres away, leaving a bar in Byron Bay.

The 18-year-old was spotted on CCTV walking through town after leaving the Cheeky Monkey bar at about 11pm. He was reported missing in June after he failed to check out of his hostel and his belongings, including his passport, were left behind.

Watson-Munro said police should investigate whether there is a link between the three missing men.

"Given the coincidence of three people disappearing in such a short period of time, similar profiles, very vulnerable as people are visiting Australia as backpackers. I think it’ll be amiss to not investigate this more thoroughly," he said.

"The facts of the case are that we have three missing people from overseas who have disappeared within a close proximal range of one another in mysterious circumstances. That’s all I can say and, frankly, that’s all [police] can say."

Police have said they do not believe there are links between the three.

Watson-Munro reiterated his thoughts to the Daily Telegraph, news.com.au reported.

"You cannot discount the fact that you have three young men of very similar profiles who have gone missing or are dead from two coastal towns which in the scheme of Australia’s geography are quite close," he told the newspaper.

"Statistically the odds of three backpackers missing in the same region in a short space of time is very unlikely and we know that these type of killers prey on vulnerable people or those that are likely not been missed for some time."

2. Woman dressed up a doll to claim Centrelink parenting payments after her baby died.

A woman who claimed Centrelink parenting payments for almost 15 years after her severely disabled baby died would dress up a doll and pretend it was her daughter, a NSW judge has been told.

Alison Christie Mains, 41, is awaiting sentence in the District Court after pleading guilty to three counts each of obtaining financial advantage by deception and defrauding the Commonwealth via the Department of Social Security.

"The offending began as a result of Ms Mains' daughter dying in horrific, tragic circumstances, aged five months," her barrister Marty Bernhaut said on Wednesday.

The disabled baby girl died in mid-1998 and the debt came to the fore in 2013 - a period of 14-and-a-half years, he said.

The agreed facts state Mains claimed $209,114 in payments she wasn't entitled to, failed to notify Centrelink of the death and made false oral representations over the years her baby was still alive.

This constituted overpayments of Child Carer Allowance ($39,403.80), Parenting Payment Single ($83,741.46) and Family Tax Benefit ($85,969.32).

She also called Centrelink within two months of her child's death seeking advance payments doing so more than a dozen times and approximately every six months.

At times Mains told the government service her daughter was in "palliative care that day" or that she had used up her previous payments on medical expenses and costs associated with her child's neurological dysfunction.

These comments were all made after the baby's death in August 1998.

Mr Bernhaut said Mains "absolutely" accepts she was not entitled to the money for her deceased child.

But he also submitted she is illiterate, has never worked, has a background of "significant deprivation" and would have been entitled to $69,696.20 in Newstart allowance during the offending period.

He said a Centrelink investigator also established she could have received more than $189,000 in Disability Support Pension entitlements.

"The DSP she may as well have been eligible for ... was some $2500 more than the single parenting payment," Mr Bernhaut said.

He said his client has previously told medical practitioners the baby's death was "a particularly difficult, stressful event" and has since engaged in behaviour including dressing up a doll and pretending it was her daughter.

"She reports being emotionally distraught and in poor physical health at the time," the barrister said.

"It's patently apparent she deteriorated significantly in the period following her child's death."

Prosecutor Frank Farah said the defence case "in the best light" is that Mains may have been entitled to "something" from Centrelink.

"It was so speculative that you certainly can't give it a mathematical figure but you can take it into account subjectively," he told the judge.

Mains' deceptive conduct was conscious and over an extended period of time, he said.

"She intentionally deceived Centrelink so she could get more money."

The court heard Mains has spent periods in residential rehabilitation for alcohol dependence and may so again.

One count of robbery and four counts of larceny will be taken into account upon sentence.

The facts state Mains stole eight bottles of alcohol in 2017 including Jim Beam Bourbon and Smirnoff Vodka.

Mains will be sentenced on September 18 by Judge Nicole Noman SC.

3. "Please someone." The final texts a teen sent before dying at a Sydney musical festival.

Lost and intoxicated, a Sydney teenager sent increasingly incoherent texts to friends as she wandered a music festival ground before collapsing and dying, her inquest has been told.

Alex Ross-King, 19, died after consuming three MDMA caps and multiple alcohol drinks and collapsing at FOMO festival at Parramatta in January.

The inquest into her death on Wednesday was told she lost contact with her friends about 3pm and began trying to reach them by phone.

About 3.30pm, she texted to a friend "F***s sake, I just want to find yours" before addressing a group chat: "Bro can someone just me from under the tree."

"Please someone," another message read.

Ms Ross-King's friend, who cannot be identified, told NSW Coroners Court on Wednesday she wasn't getting much phone service but was eventually able to message back they were at the "upstairs toilet".

"We will be here, there's dogs here," the friend warned.

"If you have something, give it to someone else."

Alex sent "I don't hwc wnythiy hqhwh" and "Where wre you".

The friend told the inquest Ms Ross-King had earlier taken three MDMA caps within a few hours, including two at the festival gates when she became nervous she'd be caught by sniffer dogs.

When friends eventually found her, they weren't concerned she was seriously unwell despite her rapid breathing and repeated complaints about being hot and being "really f***ed up".

"My legs aren't working," Ms Ross-King told her friend.

She eventually received medical treatment at the insistence of a health worker patrolling the grounds, the court heard.

The young woman resisted medical staff as they applied ice to her before she was rushed to nearby Westmead Hospital, where she soon went into cardiac arrest and died.

Ms Ross-King's friend told the inquest the teenager had used MDMA regularly for months in early 2018 but stopped about August and had never consumed three caps in one day.

The friend later burst into tears while telling the court the effect of losing a "sister" and a friend who "always put others first".

"She took a massive part of me when she left," the young woman said.

"I just hope something comes from this and we make a change for her."

Ms Ross-King's parents echoed those remarks outside, urging Premier Gladys Berejiklian to act.

The inquest is examining six recent MDMA-related deaths at NSW music festivals between December 2017 and January 2019.

Ms Ross-King, Nathan Tran, Joshua Tam, Joseph Pham, Callum Brosnan and Diana Nguyen were all aged between 18 and 23.

"What else can I say? Go home, hug your children," Deputy State Coroner Harriet Grahame said as she adjourned the inquest until Thursday.

4. Emil Petrov charged over the 2007 murder of his ex-wife Cindy Crossthwaite.

A man has faced court charged with the murder of his estranged wife, Melbourne mother-of-three Cindy Crossthwaite, more than 12 years ago.

Emil Petrov, 55, faced a brief hearing in Melbourne Magistrates Court on Wednesday as the couple's daughter watched on.

As magistrate John Hardy read one charge of murder, Petrov shook his head and said "no".

"I'm not asking you to plead," Mr Hardy responded.

Petrov made one glance at his daughter, sitting in the public gallery, during his short court appearance.

He was remanded in custody until a committal mention on October 9.

Ms Crossthwaite, 41, was found dead at her Melton South home on June 20, 2007 by her father, Philip Crossthwaite.

He went to check on his daughter after she failed to pick up two of her children from school.

Daughter Jesmine Crossthwaite-Petrov, now aged in her 20s, told reporters outside court it "wasn't easy" to see her father behind bars.

"I'm just so thankful that this day has finally come, it's been a long 12 years and finally maybe some justice will be served for my mum," she said.

"I'm just so happy - over the moon - about that."

She thanked investigators for their 12 years of work on her mother's case.

"This outcome has actually happened. It's overwhelming and amazing I'm just feeling a whirlwind of emotions at this point, I can't even explain it to be honest," she said.

A $1 million reward was announced in 2017 for information about Ms Crossthwaite's death.

That reward remains on offer, police said on Wednesday.

5. Queensland man pleads guilty to kidnapping seven-year-old girl from Kmart.

A Queensland man has pleaded guilty to kidnapping a seven-year-old girl from a shopping centre and molesting her in bushland.

Sterling Mervyn Free, 27, lured the girl from Kmart at Westfield North Lakes, north of Brisbane in December last year.

He then took her to nearby bushland where she was sexually assaulted, before returning her to the shopping centre more than hour later.

He was arrested two days later and charged with deprivation of liberty, taking a child for immoral purposes and indecent treatment of a child under 12.

He pleaded guilty in the Brisbane District Court on Wednesday to these charges.

Free was remanded in custody until his sentence hearing in October.