Daryl Floyd’s attempt to have the work paid for by the state government failed earlier this month as it was described as an “operational matter”, but Victoria Police would consider reimbursement if Terry is found.

Even without state government backing, Mr Floyd said he would continue to excavate the mine shaft and had been encouraged by another recent development.

A silver necklace found at 140 feet in the mine in 2012 was nearly identical to one owned by Mr Floyd and purchased from a Maryborough jeweller in the early 1970s.

Terry also bought a similar necklace from the jeweller.

“The same jeweller still works in Maryborough and he had a look at it two weeks ago, and confirmed it was a particular chain he would have sold in the 1970s,” Mr Floyd said.

However, police chose not to perform testing on the necklace, stating it would not prove useful in the case.

Mr Floyd has spent more than $100,000 excavating the mine shaft east of Avoca since 2010.

The search was initially supported with $50,000 from Victoria Police and $25,000 from the state government, when it was believed the mine shaft was just one-third of its actual depth.

Since the mine was found to be far deeper, the search has received no additional funding.

Mr Floyd is searching for an area with potentially hundreds of cow skulls, as a nearby abattoir disposed of carcasses in the mine shaft during the period when Terry went missing.

He believes a tunnel running north of the shaft holds the answers.

Mr Floyd said it was disappointing the government was not supporting his efforts, despite the “solid leads”.

Other missing persons cases have received state government funding, including the unsuccessful excavation at Cann River in Gippsland during the search for Prue Bird.

The search for Jaidyn Leskie near Moe in the 1990s also included $400,000 to excavate a tip.

State governments funded the search for Donald Mackay, while the South Australian government funded the excavation of numerous mine shafts near Coober Pedy in the search for Karen Williams.

Community campaigns continue to fund the search for Terry, including multiple gofundme accounts.

Mr Floyd said the search was not just for his benefit, but for the wider community.

“In the end, this is about a 12-year-old kid who innocently lost his life on the side of a road,” he said.

“It’s no longer just my quest, the whole town of Avoca is behind me – and those across Victoria interested in the case.”

Terry went missing on June 28, 1975, at the corner of the Pyrenees and Sunraysia highways.

He was last seen in a panel van, just 200 metres from the mine shaft at Bung Bong Hill.