But, like many, he'd be happy to be proven wrong.

As a former assistant commissioner with NSW Police and an investigator on the Woodward Royal Commission, Mr Small is well-versed in the 36-year mystery surrounding Mr Mackay's murder.

"The reality is, we don't know at this stage how significant the development is," Mr Small told The Daily Advertiser last night.

"All we can do is wait and see what comes out of the digging that's going on ... I would be quite sceptical that they'd find anything."

The hunt is under way in a paddock west of Hay following anonymous information received by police in December 2011.

Mr Small said the tip-off was probably from a community source and put the delay down to police attempts to build knowledge before pursuing the claims.

A comment by neighbour John Mirabelli in yesterday's Advertiser led Mr Small to believe that, despite the extended period of inquiries, police still didn't know precisely where to look.

Mr Mirabelli was questioned by detectives on Tuesday about a bore or well about three or four kilometres out of Hay.

Mr Small said he believed there were only two or three people who knew what happened to the body and two of them were dead.

"The other people who were responsible for sanctioning the murder would have kept their hands as clean as possible and wouldn't have wanted to know where (the body was)," he said.

While finding the remains would be a "terrific result" and provide many with some comfort that investigations have progressed one step further, Mr Small didn't expect any charges to be laid.

"I don't see where there'd be evidence that the recovery of the remains would, themselves, produce evidence to justify charges of people who may have been involved and are still alive," he said.

"Those who sanctioned the killing would have been too far back to be charged at this late stage.

"While I'm sceptical about finding the remains, I'd be more than happy to be wrong."

Regardless of the outcome, there will be a benefit as a result.

"It might at least, once again, focus the attention of the government and law enforcement on the Calabrian mafia in Australia," he said.

Mr Small was unsure of reports linking Mr Mackay's murder, the Griffith-based mafia and the property currently being searched and said he didn't know where the information had come from.