In his final determination dated October 1, 2013, sighted by the Bay of Plenty Times, the executor of Olwen Horan's estate John Buckthought says an investigation into the claims found no evidence which enabled him to find any claim against Mr Horan.
Mr Horan, who was expelled from NZ First in December 2012 after his half-brother Mana Ormsby claimed he had inappropriately used their mother's bank cards, has come out fighting.
Mr Horan said he was not ruling out defamation proceedings against one or more parties.
He said he planned to remain as an independent MP, and would contest the Tauranga electorate seat at this year's general election.
At the time of his expulsion, NZ First leader Winston Peters said that after seeing "substantive" information, he had no confidence in Mr Horan's ability to continue as a MP.
It was later revealed Mr Horan had allegedly used a parliamentary phone to regularly call a TAB betting line.
"There have been systematic, malicious unbelievable nasty defamatory attacks on me and I'm sick of it. These were ludicrous, frivolous allegations. I have been completely exonerated and knew I always would be," he said.
Mrs Horan, 87, who died on August 3 last year, signed her original will less than two months earlier on June 20, and on July 2 hand wrote a codicil to her will authorising her nephew and to recover some monies received from her daughter and Mr Horan.
In the codicil, Mrs Horan stated she wanted any monies loaned to them or taken by "misadventure" to be recovered.
Mr Horan's lawyer Paul Mabey QC said Mr Buckthought and independent accounting experts fully investigated Mrs Horan's estate and the fraud allegations.
Mr Mabey said it was not a case of the parties settling to save money as reported by some news media in October 20-21 but his client was cleared of any wrongdoing.
Mr Horan has since been paid his $40,000 share of his mother's estate without any deductions.
Mr Mabey said there had been no legal challenge to that finding.
"Mr Peters continues to make unjustified remarks about Mr Horan's expulsion from NZ First, and alleged wrongdoing but nothing Mr Peters says is evidence of anything," Mr Mabey said.
Mr Horan said he had no plans to return to NZ First even if he asked to do so, nor would he join any other political party despite approaches to do so.
"Since becoming an independent MP I don't believe in political parties any more, and I think it is far better for the constituents of Tauranga that I continue to do so, he said.
Mr Peters said he stood by everything he said at the time he fired Mr Horan.
He would not be drawn on his own political plans and said he was not interested in anything Mr Horan had to say.
- Sandra Conchie of the Bay of Plenty Times
