A reward for information about the suspicious death of a New South Wales opal miner more than 30 years ago has been doubled to $1 million as police renew their efforts to solve the cold case and bring justice to his family.

Paul Murray ­– described as a much-loved, “vulnerable” and generous man – owned an opal mining field about eight kilometres north-west of Lightning Ridge and was living in a camp on the site when he went missing in early 1995.

The last person to see him alive was a local resident, who had picked him up and dropped him off on the outskirts of Lightning Ridge on March 19.

Police carried out an extensive search, but it was a pair of graziers who eventually found his naked and decomposing body in scrub about two kilometres from the campsite the following month.

There were no signs of trauma, although police now say the fact that he was found with only a towel wrapped around him and burrs in his feet suggested he may have been running away or left his camp in a hurry.

Police inquiries and a coronial inquest failed to find the cause of Murray’s death.

“Since his death we have been searching for answers not knowing what happened to our devoted brother, and why somebody would harm him is beyond comprehension,” Paul’s brother, Simon Murray, said as police announced the $1 million reward on Wednesday.

“Paul suffered an irreversible brain injury at the age of 16 years old, which affected his connectivity, walking and overall appearance, which made him very vulnerable to those seeking to take advantage of him.”

David and Simon Murray say their family wants closure over the unsolved death of their brother Paul. Photo: NSW Police

Following a review in 2012, the NSW State Crime Command’s Unsolved Homicide Unit established Strike Force Huddleston to further investigate Paul Murray’s death. A $100,000 reward initially offered for information was later increased to $500,000.

The victim’s sister, Rosemary Pearse, said on Wednesday that his large family hoped the now-doubled reward would give someone the courage to come forward and clear their conscience.

“My little brother Pauly was so loved,” she said.

“He was a generous man who helped others when they needed it. His death has left pain and unanswered questions for more than 30 years… My Pauly deserves justice, and our family deserves the truth after all this time. Please help us.”

Homicide squad commander Detective Superintendent Joe Doueihi described the scene of Murray’s death as “quite brutal and gruesome”.

He said people with knowledge about the man’s disappearance who were reluctant to speak in the past may feel differently now, describing the $1 million reward as “a significant incentive”.

“We are appealing to the Lightning Ridge community and anyone who knew Paul at the time to search their memory and speak with us. If you know something, now is the time to tell us.”

Anyone with information is urged to contact the Crime Stoppers website or call 1800 333 000.