An investigation in fraud allegations against Brendan Horan has found "insufficient evidence" to lay any charges.

NZ First leader Winston Peter made a complaint to the serious fraud office in December 2012 in relation to Brendan's late mother's bank account.

Brendan Horan was not fazed by the police investigation when it was launched in 2014.

Brendan is understandably pleased with the decision and says he's now looking forward to putting the investigation behind him.

'It's difficult to say how I feel, it was a decision I always knew police would reach it's just taken a long time. But meanwhile myself and my family have been put through hell," he says.

"It's certainly not been an easy time, the police investigation was very thorough and it was like being stripped naked as they went through my background, my finances and me having to explain the most innocuous of things."

After Brendan was cleared of any wrongdoing by an investigation undertaken by accountants for the executor of the estate, John Buckthought, police launched an official criminal investigation.

"Mr Peters made allegations about the misappropriation of funds from Mr Horan's late mother's bank account, and the complaint was referred to the police for investigation," says a statement from police.

"There has been a comprehensive investigation by the Western Bay Of Plenty Criminal Investigation Branch into these allegations over the last two years, including review of the file by senior detectives.

"After consideration of all relevant information and the Solicitor General's prosecution guidelines, police have determined that there is insufficient evidence to charge any person with a criminal offence."

When the official investigation was launched in 2014, Brendan said he was not fazed by the investigation.