The deal went sour between signing a Sale and Purchase Agreement and settlement and it is the Crown's case she set it alight as there was a clause in the insurance that allowed the purchase of the property to continue, less the insurance payout, if damage occurred after the property became unconditional and before the settlement date.
The overall result was the woman gained a windfall of about $85,000.
The woman took the stand on Thursday afternoon in her defence, telling the jury she needed to buy the house for her son as he was struggling to find a rental property.
In evidence, she said her son had dogs and couldn't find a place. She said she decided it was a better option for her to buy her son a house instead, using collateral from another property she owned.
Under questioning from her lawyer, Andy Hill, the woman said her son and her then partner didn't get along. She said she had wanted her son to move in with her and her partner, but her partner didn't want that.
She said she, therefore, needed the house as there was "definite tensions" because her son and her partner couldn't even be in the same room with each other.
Hill earlier addressed the jury in his brief opening statement saying they would call evidence from another fire expert who would cast doubt on the Crown's evidence the fire was deliberately lit.
He said he would also present evidence that even if the jury was satisfied the fire was deliberately lit, they couldn't be sure it was done by the woman.
When the trial started on Monday, Crown prosecutor Anna McConachy set out the details to the jury about how the woman set to gain financially.
She said the woman was in the process of buying the house for $345,000 via a private sale. She signed a Sale and Purchase agreement and paid a deposit of $17,250.
While she waited for settlement, the woman and the vendor kept in touch and the vendor allowed the woman to move some of her belongings to the house.
McConachy said cleaners and a handyman were at the house on May 8 last year - the day of the fire - getting the house ready. However, on this date, a dispute arose between the woman and the vendor over the cleanliness of the house.
The Crown says the woman asked the purchase price to be lowered by $10,000 as a result.
The vendor refused and the woman was asked to leave the house while lawyers sorted the deal.
McConachy said the property had been insured for $275,000 and therefore the insurance payout to [the vendor] was $275,000. She had already received a deposit of $17,250 and the balance that was therefore required to be paid by [the woman] was $345,000 minus the deposit, minus the insurance payout.
This meant she was only required to pay $52,750 for full settlement of the property. McConachy said this effectively meant the total purchase price of the property became $70,000, which was a much-reduced value.
She said a valuation obtained by the owner showed the land was valued at $155,000 to $180,000, and taking the lesser of those amounts minus the $70,0000 meant the woman obtained a windfall of at least $85,000.
The Crown said neighbours saw the woman at the house only minutes before the fire started.
Emergency services were alerted about the fire at 4.51pm. When the vendor asked the woman to remove her possessions, the woman sent her a text message at 5.06pm saying she couldn't because she was in Tauranga.
However, evidence, including data from her phone, showed she wasn't in Tauranga at that time but she was at 5.45pm.
The trial is continuing and is likely to go into the start of next week.
