Violent 2007 killing of much-loved Cooks Hill grocer Frank Newbery 'not unsolvable', internationally-renowned criminologist Dr Xanthe Mallett says

And Dr Xanthe Mallett says she has no doubt the 87-year-old's killer has told someone about the brutal act.

This week marked the 13th anniversary of Mr Newbery's death, which was the second violent homicide that took place in the tight-knit suburb of Cooks Hill within a fortnight.

Mr Newbery was found unconscious under cardboard boxes in his Union Street store Frank's Ham and Beef - which he had run for more than half a century - about 4.30pm on March 12, 2007. He had been hit with a blunt instrument as many as five times, causing severe head injuries.

The well-known member of the Cooks Hill community died that afternoon.

Investigators have not found Mr Newbery's killer and an inquest in 2012 delivered an open finding - with Deputy State Coroner Mark Buscombe ruling the grocer had been attacked by an unknown person or persons.

The NSW government posted a $100,000 reward in 2007 for information that led to a conviction in the case - it's a reward that still stands.

Dr Mallett, a world-leading criminologist and forensic anthropologist who is a senior lecturer at the University of Newcastle, said she believed Mr Newbery's killer would not have kept the crime to themself.

"In my experience, people who do commit serious and violent crimes tell someone," she told the Newcastle Herald this week.

"I have not come across one yet where nobody knew - eventually they will confess to someone.

"They may be unburdening, they may in fact be showing off, it depends on their psychology. Somebody knew, you don't commit a crime like this and never tell anyone. It's unheard of in my experience."

As the Herald has reported in the years since the violent tragedy, one key theory has been that Mr Newbery was the victim of a robbery gone wrong. The fact that he had $1500 cash in his pocket after the attack casts a shadow over this hypothesis, but Dr Mallett says it remains a potential explanation.

There have also been reports in the years since the inquest that police were investigating whether the attack was targeted, but it's unclear if this is still being considered a possible scenario.

"If it was a robbery, why didn't they search him? But that could have been because it had kind of gone wrong and they've panicked," Dr Mallett said.

"It does look like a robbery gone wrong, but obviously without more information it's really difficult for police to pin down the motive and the potential offender.

"But I don't think this is unsolvable at all."

James Morris grew up in Cooks Hill and had been going to Mr Newbery's store for 24 of the 29 years of his life in March, 2007, when he arrived to find the door mostly closed - an unusual circumstance.

Mr Morris, who ran a nearby business, told the Herald this week he knocked and called out to Mr Newbery, but when he got no response he went to the Newcastle Permanent headquarters next door and asked some of the regulars who frequented the store for lunch if anyone knew what was going on. Emergency crews were soon called to the scene.

"Frank was a mighty, mighty, mighty soul," Mr Morris said.

"He was a true gentleman. Frank was one of those guys from the old school who really did seem to care.

"Frank was one of those guys who was like the heart and soul of the community. In a lot of ways [his murder] felt like a gut punch to the community."

Mr Newbery's bashing came 10 days after another violent death in the same suburb.

Lillie Wood was another well-known Cooks Hill identity. The 88-year-old was found dead on the doorstep of her Dawson Street home after an alleged robbery.

A Bar Beach woman was charged with manslaughter and aggravated robbery over Ms Wood's death and was sentenced to a maximum of five-and-a-half years jail in 2008.

However the identity of Mr Newbery's killer remains unknown.

Newcastle police declined to be interviewed about the case this week, instead issuing a statement saying investigators were continuing their appeal for information and highlighting the $100,000 reward.

"No arrests have been made," a NSW Police spokesperson said.

"This case remains an unsolved homicide."

Police never found the weapon used to kill Mr Newbery.

The most significant leads in the hunt to find his killer appear to have been accounts from two witnesses who gave evidence at the 2012 inquest and the recovery of an unknown person's DNA at the scene.

One witness told the inquest she had seen a man with long, blond, curly hair wearing a cap and a grey polo shirt inside the shop just before 4.15pm - the time Mr Newbery is believed to have been fatally bashed.

The other witness - not Mr Morris - told the court he arrived to find the doors of the store closed a few minutes later and he saw a man with a similar description inside, but instead with long, dark hair.

The shop's tinted windows are believed to be an explanation for the difference in witness accounts.

Even though the DNA does not match anyone on the database, Dr Mallett said it could provide a breakthrough in the form of DNA phenotyping - a process in which DNA could be used to build an image of a person's face.

She said genetic genealogy - using DNA and traditional genealogical methods to find biological links between people - could also be useful.

"I think we've got some good opportunities to progress some of these cases and I think we're going to see a lot of that over the next few years as Australia starts to uptake on these advances," she said.

"We're seeing it all the time in the US. There's massive scope here to start using these technologies.

"There's still a community that was rocked by this and somebody may well still be out there. Somebody who commits a violent crime on an 87-year-old man is a danger to the community."

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