The prosecution case against David Bain cost the Crown about $1.2 million, the Solicitor-General says.
Mr Bain was originally convicted at a trial in 1995 of murdering five members of his family before the convictions were quashed by the Privy Council in 2007.
He was found not guilty of the Dunedin murders after a 13-week retrial which ended earlier in June.
Solicitor-General David Collins, QC, says the figure of $1.2 million is the total cost since 2006.
He says that inlcudes three Privy Council appearances, all pre-trial applications and the prosecution costs for the three-month period of the retrial.
The total does not include costs incurred by police.