Bill and Joan Garriock hope the Unsolved Homicide Unit’s new system will bring closure to them and other families of murder victims.

NSW Police will look into 500 murders, including several of Macarthur and the South Coast’s cold case murders, from the past 40 years in the hope new DNA technology, witnesses or a fresh set of eyes will lead to the case being solved.

Nathan, a 17-year-old from Raby, was celebrating a friend’s 18th birthday in Camden South when the party was gatecrashed. 

Several partygoers were injured when a driver crashed into a group of people. Nathan was killed after being struck on the head by a plank of wood and kicked repeatedly.

“The new system sounds good because now police will look back at cold cases,” Mr Garriock said.

“Hopefully Nathan’s case can be reopened. We hope some new information in his case comes to light.

Read more: South Coast murder cases back in focus

“There is nothing worse than not knowing who killed our son.

“I hope other families can find closure too.”

The Unsolved Homicide Unit is responsible for investigating the murders, disappearances and suspected murders of Rachelle Childs, Anthony and Frances Perish, Tracey Valesini, Debbie Marie Ashby, Nathan Garriock and Peter Beazley, which occurred in the Macarthur district.

Police investigated all leads and the cases had gone cold. Detectives were relying on information from the public for a breakthrough.

Now the cases will be reviewed, prioritised and have the potential to be re-investigated under the new framework.

Homicide Squad Commander, Detective Superintendent Scott Cook, said the new process would draw on the expertise of specialist detectives from across the police force to conduct formal case reviews.

“While the Unsolved Homicide Unit is a finite resource, the NSW Police Force has a wealth of investigators whose skills can be harnessed to increase our capacity to put fresh eyes on cold cases,” Detective Superintendent Cook said.

“All matters, including new matters as referred by the Coroner, are classified into the respective category for prioritisation and triaged on a database, before being referred to a reviewing officer.”

Cases will undergo “rolling reviews” with evidence to be tested against the latest technology in DNA matching, fingerprint recognition, electronic archives searching and video restoration. 

Rachelle Childs, 23, went missing from Bargo Hotel on the evening of June 7, 2001.

Ms Childs’ partially clothed, charred body was found in a shallow ditch in bushland off Crooked River Road, near the town of Gerroa, on the morning of Friday, 8 June, 2001.

Police have not been able to confirm what happened to Rachelle that Friday morning or what her movements were the night before. Police know she was supposed to meet someone at the Bargo Hotel and her vehicle was found in the car park of hotel.

In 2016, the $100,000 reward offer for solving the crime had been doubled to $200,000.

There was a renewed push for information in the disappearance and suspected murder of Tracey Valesini in 2017. 

Ms Valesini was last seen at Campbelltown Courthouse on January 8, 1993. She had been attending a custody hearing for her daughter, Crystal-Lee, then two.

The matter was to return to court on February 12, but Ms Valesini failed to appear. Her family never heard from her again.

On what would have been Ms Valesini's 45th birthday, her family launched a public appeal for information, accompanied by detectives from the NSW Unsolved Homicide Team.

The state government announced a $100,000 reward for information.

Clint Milazzo was assaulted outside the Ettamogah Hotel on Kellicar Road in Campbelltown on February 23, 2003.

Mr Milazzo, 24, was drinking with a friend and left the hotel at closing time. He and his friend were assaulted while standing in the undercover car park waiting for a taxi near the hotel.

According to investigators, Mr Milazzo was punched in the head, causing him to fall to the ground.

He suffered serious head injuries and was taken to the Intensive Care Unit at Liverpool Hospital where he underwent several operations.

His health continued to deteriorate and he died on March 3, 2003 from severe head injuries he suffered during the attack.

Mr Milazzo was an applicant to enter the NSW Police College in Goulburn shortly before his death. His widow is a NSW Police officer.

A coronial inquest in 2005 returned an open finding and recommended a $100,000 reward be offered to help police find the person or persons responsible for the attack on Mr Milazzo.

Mr Milazzo’s case is still under the responsibility of Campbelltown detectives, who have conducted extensive inquiries but have exhausted all leads.

If the case goes to the Unsolved Homicide Unit then it could be reopened in the future under the new framework.

Detective Superintendent Cook said the reviews would “strengthen relationships with victim families through regular and informed communication”.

“It also allows the Unsolved Homicide Unit to initiate re-investigations while all other cases continue to be reviewed,” he said.

“We are committed to ensuring the most effective and efficient allocation of resources in order to maximise our capability to provide justice for victims and answers to their families.” 

Seventeen cases are already being investigated under the new framework. No further detail on the cases has been provided.

The Unsolved Homicide Unit was formed in 2004 to centralise the bulk of the state’s unsolved murders and unexplained disappearances.

The unit has seen 30 cases sold and five more are before the court.