A $250,000 reward has been put up by Queensland police for information that solves the 31-year cold case of Wayne Youngkin’s death.

Mr Youngkin’s remains were found last year in a septic tank at Brighton, north of Brisbane, at a property where his family members once lived.

The last positive sighting of the 29-year-old was in 1986, but he was only reported missing six years later.

The investigation has been hampered because many of Mr Youngkin’s family members and other persons of interest have died.

In April, police and army divers searched wetlands in Deagon after receiving a tip-off that items relating to the case could be there.

However, they failed to find anything of significance, instead turning up old car parts, logs and a sports trophy.

Detective Inspector Tim Trezise said investigators were hoping the reward would encourage members of the public to come forward.

“We would like to hear from anyone who knew Wayne Youngkin or his movements in the early to mid 1980s, no matter how minor it may seem,” he said.

Police Minister Ryan said an appropriate indemnity from prosecution would be considered.

“I want to make it clear though, that this reward will only be paid to someone who was not directly involved in the crime but may have vital information needed for police to solve this case,” he said.

– ABC