A High Court child-abuse trial was aborted when it was revealed Child, Youth and Family had failed to hand over 300 pages of documents to the police investigation.
Justice Paul Heath apologised to the jurors when he discharged them - after the case had been running for three days - following inquiries by the defendant's lawyer that brought the existence of the files to light.
A second trial for the 61-year-old man, who has been charged with 42 counts of physical and sexual abuse of two girls in his care between 1994 and 2003, is unlikely to be heard this year.
The delay will be "heinous" for the two complainants, says a sex abuse advocate, and the discovery of new documents means the police will need to interview more witnesses.
Justice Heath has ordered lawyers for Child, Youth and Family to explain by today the failure to disclose relevant material and in particular whether any documents were deliberately withheld.
In discharging the jurors on Wednesday, the judge said the 12 men and women deserved an explanation.
"It became apparent that the disclosure was incomplete to the extent that there was something in the order of 300 relevant documents that came to light," said Justice Heath.
"I can tell you that there are quite a few documents that are very relevant to fair-trial considerations, and that arises not only from the point of view of the defence but also from the point of view of the Crown."
For those reasons, Justice Heath said, the trial could not go ahead safely.
"You will appreciate that I have made some rather pointed comments about what has happened and the reasons for the delay. I am going to follow those up further," Justice Heath told the jury.
"But that has all meant that your time has been wasted in terms of coming along. I am very sorry for that. That should not happen."
Suppression orders mean the defendant cannot be identified and the new evidence found in the documents cannot be reported yet.
There will be a disclosure hearing in the High Court next week. Justice Heath "emphasised the need for candour" by Child, Youth and Family in disclosing all relevant information and to respond properly to questions from police and defence counsel.
The defendant's lawyer, Matthew Goodwin, said the disclosure failure became apparent only once the Child, Youth and Family witnesses attended the trial in answer to the summonses served on them by the defence.
"Justice delayed is upsetting to the parties involved and squanders precious legal and juror resources."
Rupert Ablett-Hampson, chief legal adviser to Child, Youth and Family's parent agency, the Ministry of Social Development, said the circumstances that led to "some relevant information inadvertently not being provided to the police" will be provided to the court as requested.
"The ministry is committed to providing all relevant information as requested by police and the courts and we are looking into why this did not happen in this instance.
"As the matter is still ongoing before the court, it would be inappropriate for us to comment further."
Louise Nicholas, an advocate for sexual abuse survivors, said the likely year-long delay would be "heinous" for the complainants.
"The courage it's taken for those women to come forward, go through the police investigation, then the start of the court process, is huge," said Mrs Nicholas, whose own complaint of sex abuse led to a commission of inquiry into police sexual conduct.
"Now they've been told to stop the trial, put their lives on hold again, all because someone didn't do their job. Once again, it's a system failure."
Social Development Minister Anne Tolley declined to comment on the issue because it was an operational matter.