AAP

A bikie gang may be behind the unsolved murder of man in a small NSW central west town more than 15 years ago, new police information suggests.

Charles Avouris was shot dead at his home in Mumbil in early July 1996 but to date, no-one has been arrested.

A coronial inquest last year concluded the 30-year-old separated father of one died from a gunshot wound to the head by at least one unknown person, although a small-calibre firearm is yet to be recovered.

Investigators now believe bikies may be behind the death, following new information given to police.

"We are looking at new DNA technology which we believe will greatly assist in solving the murder of Mr Avouris, based on the DNA evidence we already have," Detective Sergeant Mark Meredith said in a statement.

"We are also exploring the possibility that Mr Avouris's death may have been linked to outlaw motorcycle gang activity."

For the first time, detectives say a light-coloured 1980s Holden Camira wagon may have been used.

"Investigators are also following up on information regarding a car that was seen in the area at the time of Mr Avouris's death," Det Sgt Meredith said.

At the time of his death Mr Avouris, who had a daughter, had been separated from a long-term relationship.

A year ago, deputy state coroner Paul MacMahon concluded that Mr Avouris died on July 1 or 2, 1996 at the Railway House, on Naroogal Road in Mumbil, where he was renting, only a fortnight after his 30th birthday.

Mr Avouris's neighbour Ronald Hansford, who looked after his horses, became concerned for his welfare and contacted police, who found the body.

The inquest said that an autopsy had proven beyond doubt that the death was a homicide.

In the hope of finding the firearm, poolice are hoping to speak with anyone who lived at Mumbil, Stuart Town or Wellington in 1996.

Mumbil, where Mr Avouris died, had a population of less than 450 people in the 2006 census.

Strike Force Burrendong, based at Dubbo police station, was set up earlier this year in response to a coronial recommendation that extra police resources be dedicated to solving the murder.

Detectives told the inquest that police had earlier been given insufficient resources to solve the murder.