A truck driver saw her getting into an orange Datsun 120Y stationwagon on the Taupo-Napier road.
Other witnesses reported seeing a vehicle like that veering off the state highway and stopping on rural Matea Rd.
After receiving information last year, police visited the former Hinton home and carried out sonar work.
Yesterday, they returned with a concrete cutter to dig up the floor of the laundry.
Mr Moller watched as excavators drilled 80cm, then probed a further 80cm without finding anything of interest to the case.
Last night, Mr Hinton's daughter Pauline Barratt said she was not surprised the investigators had not found anything.
She said that while her father did own an orange stationwagon, it was a Toyota Corolla.
She also had proof that the concrete floor was laid before Ms Blades went missing.
"Tony has been making these allegations for some years and why the police have suddenly decided to take him seriously, I don't know," Ms Barratt said.
"I don't know why he did this, because they were actually quite good friends for a while. What went wrong, I don't know. We are trying to see if we can get to the bottom of this ourselves."
The Auckland lawyer said she had threatened Mr Moller in 2007 with legal action - something she was now looking at again.
"It's just slagging off a guy that can't answer back, for whatever reason."
But Mr Moller, who has spent years compiling a dossier on the case, remains convinced Ms Blades' body lies beneath the property - but in another part of the section.
"So do they," he said, pointing to the present homeowners. "They believe somebody's down there, under the stairwell.
"But we can't take it much further unless you find some evidence or unless they decided to dig up more of their house".
Mr Moller said he would pursue the case until it was solved.
The homeowners declined to comment.
Kawerau Mayor Malcolm Campbell said there had been "a lot of buzz" around Mr Moller's theory for years, to the point that Mr Hinton's old home was known locally as "The House".
"You can talk to anybody about it and they've all got their theories," he said.
"To be fair to both sides, it's probably the best thing that's ever happened for us here in Kawerau, because it's going to put it to bed once and for all. There's either something in it or nothing in it," Mayor Campbell said.
Ms Blades' brother, Tony Blades, said from his Hawkes Bay home that he did not know Mr Moller or the details of his theory.
Asked if the development had brought new hope, he said: "We'll see what happens ... Until I hear something, I can't talk about it."
Ms Blades' mother, Wiramina, died last January, seven years after husband Peter.
The case came under the spotlight in 2004, when investigators were told about what was thought to be a shallow grave bearing Mona Blades' name in a Huntly garage.
It had been inscribed on concrete as a joke six years earlier and the former owner of the property apologised to the Blades family.
Bay of Plenty district field crime manager Detective Inspector Mark Loper said historic unsolved cases were "periodically reviewed to ascertain whether any new information has developed, or if law or technology has changed, that may shed new light on the case".
An unsolved murder case was never closed, and police continued to do their best for victims, regardless of the time that passed.
"Files like this always remain open waiting for new information or a situation to change, and we regularly review 'cold cases' in a renewed effort to try and solve them.
"Relationships and allegiances change over time, and sometimes people just want to get things off their chest."
Can you help solve the Mona Blades mystery?
Call Crimestoppers anonymously on 0800-555-111.
