The family of Donald Mackay is hoping a renewed focus on finding the remains of the anti-drugs campaigner, along with a $200,000 reward, could bring a horrifying chapter of their lives to a close.
As the 35th anniversary of Mr Mackay's disappearance approaches - July 15, 1977 - the New South Wales Government and police hope the reward could loosen the tongues of those with information.
Mr Mackay, 43, was last seen at the Griffith Hotel car park, where police later found bullet casings, blood and his locked van.
An inquest in 1984 found he was likely shot to death that night.
The Sydney Morning Herald reported the state's unsolved homicide squad had received information that could lead them to Mr Mackay's remains.
It also reported that Mr Mackay's son Paul, who still lives in Griffith, said it was the first time the reward had been increased since 1981.
"It is still important for the people of Griffith, as well as our family, to see those people still living in our community who conspired to murder our father brought to justice," Mr Mackay told the SMH.
In a statement, Detective Superintendent Michael Rowan said the failure to find his remains made the circumstances of his death even worse.
"It has left a family forever wondering, and a community stained by events that occurred before many of its residents were born," he said.
"We are confident that someone knows what happened to Mr Mackay's body and, in what we believe may be a last-ditch effort to solve this matter, we are appealing for them to come forward."
A man served jail time in Victoria for conspiring to murder Mr Mackay and a Royal Commission named six others who may have been involved in ordering the killing, but justice was never done for the murder itself.
The events leading up to Mr Mackay's murder were included in the 2009 Underbelly television series.
Anyone with information is asked to contact Griffith Local Area Command on (02) 6969 4310 or Crime Stoppers on 1800 333 000.
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