Another search for the remains of three-year-old William Tyrrell on the NSW mid-north coast is yet to turn up answers, as bushland is cleared and potential evidence is combed over again.
Police have dug up the garden at the Kendall home where his foster grandmother lived and where he was last seen in 2014.
A mechanical sift was brought on to the property while in nearby bushland volunteers cut down trees to help in the search.
Police Commissioner Mick Fuller confirmed there had been a significant breakthrough in the case, saying he was confident police would solve the mystery of the boy's fate.
"There is certainly one person in particular that we are looking closely at," he told Sydney radio 2GB on Tuesday.
The case of the boy who went missing in his Spider-Man suit has captured the nation's attention since he disappeared while playing in the garden of his foster grandmother's home.
Police Minister David Elliott Police was asked about a report that police were investigating whether William died after falling from a balcony at the Kendall home.
"With a mysterious incident like this, every single option has to be investigated, every scenario has to be reviewed and tested," he told reporters.
"Let's hope whatever the conclusion is gives closure to the families and community."
Mr Fuller said he didn't want to say too much for fear of compromising the investigation.
"Officers have been working tirelessly to get to this point where we are searching land, again using the best technology available," he said.
"They inherited what was a bit of a mess and have really cleaned up that investigation and they have a clear strategy and one of those is going back to Kendall."
Mr Elliott says that "inherited mess" will probably be subject to an internal police review, but the focus should be "on drawing this matter to a conclusion".
The commissioner and the taskforce had the government's full support, he said.
"Anything that's happened in the past is in the past as far as I'm concerned."
The Law Enforcement Conduct Commission could investigate "if people did the wrong thing" and police would conduct further internal reviews.
"I think something of this magnitude will probably automatically see at least an internal post operation review ... that's appropriate and the least we can offer the family and the community," Mr Elliott said.
Asked earlier about reports police were seeking an apprehended violence order against a person or people of interest in the case, Mr Elliott was reticent to say too much.
"It is a matter of public record that police are issuing AVOs," he told the Seven Network.
"We need to be cautious about how we discuss that in the public domain so smart lawyers don't use our comments to neutralise a conviction."
William's foster family have never been publicly named due to legal reasons.
Ten reporter Lia Harris, who interviewed the foster parents for her 2019 podcast Where's William Tyrrell? said she had recently received a subpoena from the coroner's court for "a very broad range of material".
"Everything that I had uncovered in my research for the podcast, audio files, documents, everything, including those raw tapes of my extensive interviews with the foster parents," she told 2GB on Tuesday
"To me, it signalled that they had either taken a new direction or they had a new theory they were working on."
The findings of a coronial inquest into William's disappearance, which concluded last year, are yet to be handed down.
A $1 million reward for information on the case still stands.
Australian Associated Press