The mother of MP Brendan Horan protested against changes to her will in a recorded statement in which she questioned what had happened.
Olwen Horan's lawyer also raised concerns about the changes by a new law firm which happened two months before she died.
The Weekend Herald has found the changes were instigated by the MP's half-brother, recently discharged bankrupt Peter Horan.
He and another half-brother, sickness beneficiary Mana Ormsby, discovered before Mrs Horan's death that she had no money left from a decade-old lottery win they believed they had a claim to.
The changes included a $150,000 payment to Peter Horan which had not appeared in her earlier wills.
It also included the clause seeking an investigation into spending from Olwen Horan's account by two other siblings, Brendan Horan and Marilyn Bleackley.
The revelation ended Brendan Horan's political career with NZ First. A police investigation is currently under way into the spending although the trust executor's inquiry found "no evidence which would enable me to found a claim against Brendan".
There was already tension in the family over finances at the time three changes were made to the will during June and July 2012. Olwen Horan died on August 3, 2012, with $3000 left in her bank account and her home, which sold for $425,000.
Miranda Horan, Brendan Horan's wife, said disagreement among the family included the fate of her mother-in-law's jewellery. On a hospital visit on June 13, 2012, she used her iPhone to record Olwen Horan - clearly telling her she was recording their conversation and why.
Olwen Horan said: "I couldn't understand how Mana and Peter could change my will."
Told it couldn't be changed without her signature, she said it had happened when she signed to remove her daughter Marilyn as power of attorney to protect her from anger over the position from Mana Ormsby and Peter Horan.
Asked if she wanted the additional changes, she said: "No. I wanted things left as they were. They cannot change anything in my will. Just the power of attorney."
Solicitor Colin Gardner, in a signed affidavit, said he was telephoned by Olwen Horan, who was "somewhat confused as she believed someone from my office had attended upon her to sign some documents" but she had been invoiced by another law firm.
Mr Gardner followed the call with a letter to the new law firm, saying Olwen Horan "has serious health problems and accordingly there may be some doubt as to her mental capacity to sign documents".
Peter Horan confirmed the change included a ring-fenced $150,000 payment to him which he had unsuccessfully attempted to keep in trust while bankrupt.
He said his mother had sought and received a medical certificate before changing her will which found her of sound mind.
He said he had legal advice saying he was entitled to half his mother's lottery winnings, and her ownership of the winnings could be linked to the $150,000 payment. "Probably because she felt guilty of what she had done, taking the money from that prize in Australia off me." Told the allegations had likely ended Brendan Horan's political aspirations, his brother said: "Good. Best thing that ever happened to the bastard."
Brendan Horan has always denied wrong-doing in relation to his mother's money.
Miranda Horan this week told the Weekend Herald she backed her husband's story, saying Olwen Horan took pleasure spending her money and "good on her" for doing so.
She said her husband's brothers were frustrated and upset when it emerged there was no money left in the estate. "It's a family thing that's gone mental."