The search, led by Terry's brother Daryl, will continue throughout the weekend.

"We are coming back to the place where Terry was last seen and that is where we are searching again," Mr Floyd said.

"We always live in hope and that is what this search is all about.

"It's such a relief to see progress made and we are doing this all for a little kid. Terry was an innocent little boy and he shouldn't of lost his life here."

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"100 per cent, I believe my brother's body was disposed in the mine, in this area.

"This has never been done before, this should of been done in the days after his disappearance but we are doing it now."

Terry, aged 12 at the time he went missing, disappeared from the corner of the Pyrenees and Sunraysia Highways on June 28, 1975. In 2001, a coroner determined Terry was abducted and murdered, but his body has never been found.

The search comes after a "significant" find was recently made, one which may hold answers to the young boy's disappearance.

"I received a call on New Year's Day saying there had been a significant find a little further up from here and that was a knife," Mr Floyd said.

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"It was unearthed, eight inches under the soil, there was a heap of erosion on it. I am going to get it tested now.

"We just want to age how old the metal is, we know we won't be able to get DNA on it but we want to see how old the knife itself is. If it's 40-50 years old, then it fits in the time when Terry went missing.

"If it's 30 years old, then we can eliminate it. We just need to know."

Mr Floyd said receiving that phone call gave him a sense of relief.

"We try not to get overwhelmed and get our hopes up, you have to control yourself but it's still glimmer of hope," he said.

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Mr Floyd and the volunteer searchers from Search Dogs Sydney will spend the weekend combing a 500-metre radius around the mine site, carrying on the promise Mr Floyd made to his parents years ago.

President of non-for-profit Search Dogs Sydney Chris D'Arcy said for the first time the search would also include specialist human remains dogs - Boof and Rufus.

"Daryl (asked) if we were interested in assisting in his brother's case and we jumped at the opportunity," he said.

"We are here to carry out cadaver searches in the last known sighting of his brother.

He said he strongly believed the group would come out of the weekend with some forensic evidence that would aide the situation.

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Mr D'Arcy said the non-for-profit had been aware of this specific investigation for a little longer than two years now.

"We will be here for this weekend for now but we believe with this evidence and the information that has come to light in the 12 months that this is the area of interest at this stage," he said.

For Mr Floyd however, this weekend wasn't just about his search for Terry, it was also about helping others find answers for their missing loved ones.

"We are all about awareness and we want to make families aware these resources are available," he said.

"There are so many families out there that need answers just like me. If we can get the word out that this is an option, then it would great."

Members of a Bendigo family linked to a 1968 cold case in which a teenage girl and her boyfriend mysteriously disappeared, will also be in Avoca, interested to learn how the dogs might also help them.

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Maureen Braddy and Allan Whyte went missing on November 23, 1968 in Bendigo. Decades later a coroner ruled foul play was most likely involved in their disappearance, but there was not enough evidence to lay charges.

"We were interested to see how the cadaver dogs worked and how this (group) did the search to see if that was a possibility for us," Lyn Butterworth, Maureen's sister, said.

"It would be interesting to see how the dogs would go in our search, because I know they will find something.

"In the coming days, we will be supporting Daryl and will be hoping something is found."

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Mr Floyd has also been in talks with the state government about organising a complete search of the mine, where he believes Terry's body is.

"We need to complete the mine search and we have been in talks with the Andrews government towards the end of last year and we are working towards an agreement," he explained.

"What we need is a mining crew to complete the mine search and there is certain expertise that is needed," he said.

"We are 80 per cent complete of the mine and hopefully they can see how desperate we are for answers."

Remaining hopeful on Friday, Mr Floyd believed more would be found and thanked everyone who volunteered their time to help and assist.

"We are being proactive and that's all that we can really do," he said.

"We are taking baby steps forward, ruling things out and that's what we are going to continue to do."

"I am thankful for everyone and to get this level of community involvement and to get all of this assistance, they are just getting things done.

"Without the community's involvement, we wouldn't be where we are today."

A $1 million reward has been offered for information regarding the case, which has haunted the Floyd family for more than four decades.

Anyone with information is urged to contact Crime Stoppers on 1800 333 000.

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