Three Iranian migrants and a family friend have been found guilty of mortgage fraud after they scammed seven New Zealand banks in a $NZ9.2 million scheme involving 11 Auckland properties between July 2007 and December 2010.

Eli Devoy, also known as Ellie Stone, Eli Ghorbani, and Elaheh Ghorbani Sar Sangi, has been found guilty of 20 charges following a 10-week trial in the Auckland District Court.

The 47-year-old was the principal defendant and had earlier admitted four more charges.

Of her brothers, Mehrdad Ghorbani was found guilty of six charges and Mehrzad Ghorbani found guilty of four, having pleaded guilty to one charge prior to trial.

A third brother, Mehran Ghorbani had pleaded guilty to three charges prior to trial.

Nasrin Kardani, a family friend, was found guilty of three charges while Hassan Salarpour, Eli Devoy's brother-in-law, and a friend, Javad Toraby, were found not guilty.

Judge Gibson's judgment says Serious Fraud Office and police officers who executed a search warrant on the Devoy residence in Eastern Beach in 2012 found "a veritable Aladdin's Cave of compromising material in the form of bank statements, loan applications, notes confirming payments of various deposits, a passport and a driver's licence. Many of the documents were forgeries."

The Serious Fraud Office laid charges against the seven in 2013 after investigations started in 2011.

The scheme, or "series of scams", began to unravel in February 2010 when a Bank of New Zealand investigator advised police about some transactions using false documents, while Westpac Banking Corp had begun to investigate another property deal at about the same time.

Kiwibank made a complaint to the SFO in November 2011.

The five will be sentenced on August 17.