New Zealand's market watchdog has spent more than $1.65 million on external lawyers, investigators and other services in the Viaduct Capital and Mutual Finance case.
The trial of four directors of the failed companies was aborted in May after running for nine months.
The Financial Markets Authority - the prosecutor in the case - has confirmed it will push for a retrial of three of the four men.
Paul Bublitz, Bruce McKay, Richard Blackwood and Lance Morrison went on trial in the Auckland High Court last August for what was originally meant to be a 12-week case.
McKay and Blackwood served as directors of Viaduct Capital while Morrison and Bublitz were on Mutual Finance's board.
The firms went into receivership in 2010, owing $17m.
Bublitz, according to prosecutors when the trial began last August, allegedly used the two finance companies to support his property investments.
The other defendants in the case were accused of helping him. All four denied the allegations against them.
The trial, before Justice Mark Woolford without a jury, stretched on much longer than expected and the number of charges was whittled down to try to contain it.
The four directors successfully applied to abort the trial last month after it was revealed that thousands of documents were provided to the defence late.
Justice Woolford, when granting their application, said there was a "real possibility of
unfairness to the defendants if the trial was to proceed".
The FMA has since confirmed it will push for a retrial of Bublitz, McKay and Blackwood.
The market watchdog, however, is taking no further action against Morrison.
The FMA, under the Official Information Act, has this week released a breakdown of external costs in the case so far.
The authority did not disclose internal costs of the case and at time of publication had not responded to a further request for this information.
Since mid-2011 when the FMA's probe began, more than $1.65m has been paid to outside parties for this case.
That includes more than $560,000 paid to law firm Meredith Connell, who is acting for the FMA.
It also includes more than $883,000 paid to professional services firm Deloitte which was involved in the Viaduct and Mutual investigation.
A further $209,000 has so far been spent on "litigation software support services, other IT support services and administrative costs", the FMA said.
- This story has been amended since it was first published.