"I made the decision to actually go onto the property to see what the state of affairs was," he said in an affidavit. "I recall walking to the front door and knocking on it. There was no answer. I found the rear door was off its hinges and placed to the side."
After finding the house full of rubbish, falling apart and "uninhabitable", he left and "decided to take possession of it myself". He called a builder to fix the doors, change the locks and make the building watertight, spending about A$35,000 on repair works.
He then appointed a managing agent and began renting out the property, while paying the council rates, water levies, land tax and insurance. Further repairs to the tune of A$108,000 were carried out in 2014.
Property records show the 498 square metre, three-bedroom, one-bathroom, one car space house was most recently advertised for rent at A$600 per week.
Gertos said he received legal advice that if he could occupy the property, pay the bills and look after it for at least 12 years he could claim "adverse possession". Last year he requested that the Registrar-General register him as the owner.
Downie's daughter told the court her father moved the family because the house was "full of white ants", after which they never returned to Malleny Street or talked about it. His grandson said the property was "never discussed in terms of ownership".
Rather than attempting to recover the land, the family applied to the court to simply block Gertos from being registered as the true owner.
They argued Gertos did not possess the property in an "open manner", and that occupying the property for the purpose of obtaining rental income did not amount to a "taking of factual possession".
The court has previously ruled that to claim adverse possession under Section 45D of the Real Property Act 1900 it must be "open, not secret; peaceful, not by force; and adverse, not by consent of the true owner".
In his decision this week, Justice Rowan Darke said he did "not think that Gertos' possession can be considered to be secret rather than open".
"Neighbours and other residents in Malleny Street may not have seen Gertos personally, or had any dealings with him, but that is no different from what commonly occurs where a residential property is held by its owner as an investment and is made available for lease," he said.
"Insofar as Gertos acted as the landlord by entering into leases, maintaining and repairing the property, and paying outgoings in respect of it, he was not acting in secret. It was obvious to many of the residents who gave evidence that the property was being rented out by an 'owner' even if they did not know the identity of the 'owner'."
Justice Darke also rejected the family's argument that if a legal representative were now appointed to Downie's estate, that person could attempt to recover the land from Gertos.
He said that would "create considerable uncertainty in the operation of the Act insofar as it concerns actions to recover land held by a deceased registered proprietor".
"If a registered proprietor was deceased but no legal personal representative had been appointed the potential would exist for a cause of action in favour of a legal personal representative to arise at an indefinite time in the future and there would be no certainty that the cause of action would ever arise," he said.
"This result would be contrary to one of the evident purposes of the provisions of the Act, namely, that where land remains in adverse possession for a defined period the titleholder will be barred from seeking recovery of the land and the title will be extinguished."
The point of the law, he said, was that "there is a public interest in ensuring that a person in long-term and undisputed possession is able to deal with the land as owner".
The court discharged the injunction preventing the Registrar-General from registering Gertos as the owner of the land and ordered the family to pay his legal costs.
In 2015, Gertos was fined A$200,000 for the illegal demolition of a heritage row of shopfronts on Parramatta Road next to the Annandale Hotel in Sydney's inner-west.
Leichhardt Council had approved the redevelopment on the condition the facade was preserved, but Gertos disregarded the order. He was personally fined A$150,000 and his company Geitonia another A$50,000. The builder was also fined A$50,000.
"At the end of the day Gertos stands out as far more culpable than the other defendants because they offended because of what Gertos did," Justice Peter Biscoe was reported by the ABC as saying.
"The sentence needs to operate as a powerful factor in preventing the commission of similar crimes by persons who might be tempted to do so. The planning system would be ineffective if developments were allowed to continue without, or in contravention of, development consents."
As a result of the illegal demolition, Leichhardt Council stripped Gertos and Geitonia of their development approval.
In 2016, a squatter who took over a dilapidated A$1m Redfern terrace — left to ruin after its Chinese-born owner disappeared in 1991 — abandoned his bid for adverse possession following a protracted battle with neighbours.
