Former Labour Party MP Darren Hughes, who resigned from Parliament this year amid a police inquiry, says he always believed his name would be cleared.
Police said on Wednesday they would not be laying charges against Mr Hughes following an investigation into a sexual complaint made by an 18-year-old man earlier this year.
The former list MP was investigated following a late-night incident in a Wellington suburb, but has always maintained he has done nothing wrong.
Detective Inspector Mike Johnson says the evidence gathered during the investigation has been properly considered by police and the Crown Solicitor's Office.
He says after careful consideration, the allegations do not reach the evidential threshold required to bring charges, and none will be laid.
Mr Johnson says police also investigated other allegations contained in an anonymous letter sent to media outlets and there were no matters requiring further police attention.
Hughes not ruling out return
In a statement on Wednesday, Mr Hughes says being falsely accused of a serious crime has been one of the most challenging experiences of his life.
He says resigning from his portfolios and Parliament was a very high price to pay, but the frenzied media attention left him with no choice.
Mr Hughes says he believes he still has much to offer and would like to continue to serve the Otaki community and the country. However, he says he will take some time to consider his plans.
Senior Labour MP Trevor Mallard says it would be a big call for Mr Hughes to return to Parliament - given how he has been treated - but the door is open.
"I certainly hope that Darren has a future in the Labour Party. Clearly, he's got some time and space needed in order to rebuild."
Mr Mallard says if he was Darren Hughes, there is no way he would want to be around Parliament right now.