Police have spent close to $200,000 so far on reviewing the Crewe murder mystery.
Arthur Allan Thomas was convicted and then pardoned of the murders of Jeanette and Harvey Crewe, who were shot in Pukekawa in 1970.
The couple's daughter asked police to reinvestigate the murders, but instead they are reviewing their original investigation.
Official Information Act requests to the police show the cost of the review so far has been $195,000,
mostly on making digital copies of the original file of notes and evidence.
Mr Thomas' brother, Des Thomas, said that came as no surprise.
Police won't release most of the information requested by Radio New Zealand, including how much staff time has been spent, the number of people interviewed, and whether lawyers have reviewed the case.
Police also won't say when the review will be made public.