Police have been able to establish historical links between key figures of the Griffith mafia – alleged to have organised the hit – and the property now at the centre of the latest investigation.

The theory, believed to be supported by fresh information from an inside source, suggests Mackay was shot in the car park of the Griffith Hotel, bundled into the boot of a car and driven to a Hay property 150 kilometres away before the killers drove to Echuca and on to Melbourne.

Mafia insider, Gianfranco Tizzoni, gave evidence that he paid Melbourne hit man James Frederick Bazley $10,000 to carry out the murder.

He said he acted as a middle man for notorious crime figure Bob Trimbole who had agreed to organise the contract killing on behalf of Griffith crime figures.

Trimbole and Tizzoni were once in business together, repairing pinball machines in the Griffith and Hay districts.

Tizzoni claimed his only role in the killing was to hire Bazley. Police now believe he was present in the Griffith car park on the night of the murder and helped dispose of the body.

In recent years NSW forensic experts have carried out a review of evidence kept from the Griffith crime scene and have found sufficient DNA to be able to identify any remains if discovered.

In 1986, Bazley was sentenced to life over a double murder, nine years for the conspiracy to murder Mackay and a further four years for a $270,000 armed robbery.

He has always maintained he was not involved in the Mackay murder.

He was freed in 2001 and eight years later NSW police went to his Melbourne home and asked him if he had any information on the case. He declined to comment.

Now 87 he is still seen in the company of some of Victoria's best known crime figures.

Mackay was shot in the car park of the Griffith Hotel on July 15, 1977. A politically active local shop owner he had provided police with information on local marijuana growers.

The heads of the Griffith syndicate, known variously as The Family or the Honoured Society, thought about trying to bribe him or set him up with a woman. Finally, they hired Bazley to carry out the hit.

Bazley also killed drug couriers Isabel and Douglas Wilson, whose bodies were found buried in Rye in May 1979.

The Wilsons were killed on the orders of the Mr Asia drug syndicate boss, Terrance John Clark, after corrupt police told him the couple were talking to Queensland detectives.

Tizzoni agreed to give evidence after he was found with a boot-load of Griffith marijuana in his Mercedes on the Hume Highway, just out of Melbourne.

Police believe his later version of events surrounding the Mackay murder was designed to minimise his involvement. "He wrote himself out of the actual murder," one said.

Police believe it would have been difficult for Bazley, who is quite a small man, to have been able to have put the large body in the boot without help.

Tizzoni died in hiding in Italy in 1988, and "Aussie Bob" Trimbole, died in Spain the previous year.

Bazley was never charged with the NSW murder but rather with the Victorian conspiracy to murder, which occurred in Melbourne where he accepted the contract from Tizzoni.

Bazley was a Painters and Dockers gunman in the 1970s, and was shot twice during the notorious dockers war. He has a 50-year history of armed robbery and violence.