A bankrupt property developer jailed for a $47 million mortgage fraud has lost an appeal against both his conviction and sentence.

Malcolm Duncan Mayer, in his 50s, was jailed in 2014 for six years for dishonestly using a document and using forged documents.

Mayer, mostly acting with alleged co-conspirator Simon Turnbull, dishonestly used documents to obtain $47 million of loans from Trustees Executors.

He made loan applications to the company with false information to buy 26 Auckland properties between 2003 and 2007. As a result, TEL suffered "colossal" losses of at least $19 million.

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Turnbull, while accused of similar offending, is believed to be overseas - his present location unknown.

Information about Turnbull's whereabouts and whether it was properly disclosed formed the basis of Mayer's appeal.

Mayer's lawyer argued in front of Justices Rhys Harrison, John Fogarty and Robert Dobson in March that prosecutor John Dixon had earlier misled both the court and the defence when he said the Crown was unaware of Turnbull's location.

The defence counsel claimed that this "misconduct" was egregious enough to justify a retrial.

Mr Dixon received information on three occasions about Turnbull's possible whereabouts in 2011 and 2013 but doubted its accuracy and did not think it would help Mayer's defence.

"Much more likely, any evidence Mr Turnbull sought to give would inculpate Mr Mayer," Mr Dixon said in an affidavit.

"I always doubt the information I had received about possible places where Mr Turnbull might be. I did not consider the unverified tip offs as to these possible places to be relevant or required to be disclosed," he said.

The three Court of Appeal judges exonerated Mr Dixon of any suggestion of misconduct.

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"We are satisfied that the prosecutor was under no obligation to disclose this information... moreover even if it had been disclosed, there is no reasonable possibility that the information would have affected the reliability of Mr Mayer's convictions.

"In our judgment the information would have had no effect whatsoever on the overall fairness of the trial process," the judges said in their decision today.

Justices Harrison, Fogarty and Dobson rejected the appeal against conviction, as well as throwing out a challenge to the length of Mayer's sentence and the minimum period he must serve in jail.