The infamous killing, arguably Australia’s first political assassination, kicked off a series of events that led to two royal commissions, a renewed war on drugs and the downfall of the “Mr Asia drug cartel”.

The official story is that Mr Mackay was set to name names in the Griffith drug trade, which led Calabrian mafia figures to pay Melbourne hitman James Frederick Bazley $10,000 to carry out the murder.

Donald Mackay was last seen alive at 6.30pm on July 15, 1977 at the Griffith Hotel. He bought a cask of wine and headed into the dark car park where his killers were waiting.

By 2am the next morning, police had found Mr Mackay’s locked van with the keys laying beside it. Blood stained the door and pooled on the ground beside three .22 cartridges. 

In the years following the “disappearance”, repeated searches have failed to find Mr Mackay’s body while conspiracy theories have evolved into urban legends.

Griffith police commander, Detective Superintendent Michael Rowan, said years of tip-offs and dead-ends had failed to give Mr Mackay’s family the closure they needed.

“Investigators remain in contact with the family and I can’t tell you the pain they feel for not knowing where his body is,” Superintendent Rowan said.

“It’s hard enough to know justice hasn’t been served, but never having the opportunity to lay your loved one to rest and say a proper goodbye is heart wrenching.

“We know someone knows what happened and we still hold hope the government reward may be an incentive to finally come forward.”

In July 2012, the NSW Government announced an increased reward of up to $200,000 for information that led to the recovery of Mr Mackay’s remains.

“Dozens of investigators have dedicated countless hours over the past 40 years to investigating Mr Mackay’s murder, but we still don’t have all the answers,” Superintendent Rowan said.

“Police have investigated many tip-offs about the location of his remains, and followed numerous lines of inquiry right through, but it has never led us to the answers the family needs.”

1977: Donald Mackay disappears in a suspected mafia assassination. Police find blood and spent cartridges near Mr Mackay’s locked van at the Griffith Hotel.

1979: The Woodward Royal Commission finds Mr Mackay was murdered by a Griffith-based cell of the Calabrian ‘Ndrangheta mafia. 

1984: A coronial inquest concludes that Mr Mackay died of wilfully inflicted gunshot wounds. 

1986: James Frederick Bazley is jailed for conspiring to murder Mr Mackay. He was released in 2001.

2001: Barbara Mackay, Mr Mackay’s widow, dies.

2012: A $200,000 reward is offered for information leading to the remains of Mr Mackay.

2013: Police excavate a property near Hay in a bid to find Mr Mackay's body. Nothing is found.

2014: An eyewitness comes forward, but no new evidence is found.