A High Court judge aborted a child abuse trial after it was revealed Child Youth and Family failed to reveal evidence to police.
Justice Heath apologised to the jurors who spent three days hearing evidence before the trial had to be abandoned on Wednesday.
Extensive suppression orders prevent naming of the man, who faces 41 charges relating to two young girls.
Justice Heath told the jury they deserved an explanation for why their time had been wasted.
He said after legal arguments, it became apparent 300 pages of evidence from Child Youth and Family had not been disclosed and the information was relevant to fair trial considerations.
He said he would be following up the matter.
The Ministry of Social Development said it would explain to Justice Heath why it failed to notify the police of information relevant to the case.
A legal adviser for the ministry, Rupert Ablett-Hampson, said it was looking into why the information was not released to the police but he declined to comment further.
The trial is yet to get a new date but is unlikely to be this year.