A Wellington woman whose estate is now in question, must have liked this Strathmore house - she owned it twice.

The mysterious disappearance of perhaps $450,000 is behind an attempt to corral what may be the only remaining property of a vulnerable Wellington widow who died nearly three years ago.

Mary Patricia Scott-Smith's last years had some extraordinary features, not least because she sold her Strathmore house and bought it back a year later, an Associate Judge at the High Court in Wellington was told on Friday.

But the second time her earlier sole ownership was diluted to a third share, with her son and daughter-in-law, holding the rest, lawyer Mike Garnham said.

When Scott-Smith died in October 2015, aged 79, she had no bank accounts of her own and it was not clear what happened to hundreds of thousands of dollars, or even where her pension had gone, Garnham said.

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The other two listed owners of the Monorgan Rd, Strathmore house, were named as defendants in a case to have the house sold and the proceeds held in the meantime.

Scott-Smith's son, Paul Scott was not represented and was not co-operating, and his estranged wife Kesinee​ Scott, was believed to be in Thailand and had not responded to attempts to contact her, including through Facebook, Garnham said.

Garnham was executor of Scott-Smith's estate and said the estate's assets should be "locked up" at least until a claim against it was decided. Her three children were now middle-aged.

There were serious concerns about Scott-Smith's mental capacity in her later years and irregularities relating to retirement savings and proceeds of a house sale, Garnham said.

About $450,000 cash was not accounted for but large chunks could be traced into the personal accounts of Paul and Kesinee Scott, he said.

In 2003 Scott-Smith bought the Monorgan Rd property and should have had more than $200,000 cash left over.

She sold that property in 2008 for $453,000, and went with her son and daughter-in-law to Thailand and returned three or four months later, Garnham said.

In 2009 she bought back her old house for the same price she had sold it for a year earlier, but this time her son and daughter-in-law were also listed as owners.

There was no evidence either had capital or income to put into the purchase, and nothing to suggest Scott-Smith had loaned money or funded them into the property.

But by that time Scott-Smith had just $203,000 and needed a $250,000 mortgage to complete the purchase.

Scott-Smith's dementia worsened and some professionals dealing with her suggested significance influence over her and abuse, although one person said the abuse went both ways

The evidence suggested undue influence, duress, or diminished capacity, Garnham said.

By 2012 her bank accounts were closed and all her money was held in the accounts of her son and daughter-in-law. Her signature on a bank loan agreement looked like a forgery, which was another extraordinary feature of the case, Garnham said.

The mortgage and rates on the house were now in arrears.

Associate Judge Kenneth Johnston reserved his decision.

There was no response when a Stuff reporter went to the Monorgan Rd house on Friday.