Donald Mackay went missing 36 years ago from the car park of the Griffith Hotel in south-western New South Wales.
Police are now digging up farmland near the neighbouring town of Hay after receiving a tip-off that Donald Mackay's remains could be found there.
David Crisante reports.
Donald Mackay was an influential man in Griffith in the 70s.
He owned a furniture shop and unsuccessfully contested the state seat of Murrumbidgee as a Liberal candidate in the 1973 and '76 elections.
Mackay became a fierce anti-drugs campaigner, drawing attention to Griffith's drug problems and the marijuana crops being grown by Italian-linked mafia groups throughout the New South Wales Riverina.
Mistrustful of local police, he secretly passed on information to police in Sydney.
This led to a raid on a cannabis plantation in 1975, and the police discovery of Australia's largest-ever crop.
But two years later, he was killed during an incident perceived as an organised hit by the mafia in the car park of the Griffith Hotel.
His friend and lawyer, Ian Salmon, described finding the scene of the murder in an interview for the 2010 film 'Who Killed Don Mackay?'
"So I drove into the hotel. I saw immediately in the headlights of the car that this was Don's vehicle. I drove up to it and saw the shocking evidence of a disaster. There was blood in the area of the door and the front of the car."
Three cartridges were found by Donald Mackay's car, but his body was never found.
Despite that, a 1979 Royal Commission into drugs found that he was murdered by a hitman on behalf of the mafia, which had ties to Calabria in southern Italy.
The mafia was suspected of the murder because just months before Mackay's death, he was revealed as the secret police informant that led to the 1975 cannabis raid.
Rod Broadhurst, a professor of criminology at the Australian National University, says the Mackay murder was a wake-up call for Australia, that led to a concerted effort by police to tackle organised criminal groups.
"It was a national story of great significance and the groups that were implicated were Calabrian mafia-like groups such as the 'Ndrangheta."
He says Donald Mackay represented the views of many people in Griffith who were worried about crime groups that were well-established in regional New South Wales.
"He was reflecting a lot of concern in that region about the kinds of businesses that were going on and the kinds of money that was flowing in. There were concerns in the state capitals as well. There were a number of civil libertarian groups, investigative journalists and others who were concerned about the apparent growing influence of these kinds of organised crime groups."
No one has ever been jailed for Donald Mackay's murder, but three men were convicted of conspiring to murder him, including contract killer James Frederick Bazley.
One of the men has since died and the location of the third man is unknown.
Mackay's murder was dramatised in the recent TV series Underbelly: A Tale of Two Cities.
Police last year offered a 200,000 dollar reward for further information on the death.
But the former New South Wales police head of Crime Squads, Clive Small, has told the ABC any further discovery on the Mackay case is unlikely to lead to new prosecutions.
He says the evidence used to convict the three men of conspiracy to murder can't be used to convict them of the murder.
"Now without that evidence, you'd be very unlikely to get a conviction of those people. I think the others who have not been charged to date, who are further back in terms of the murder, we're not going to get the evidence to connect them after this period of time."
