The man known as the "Beast of Blenheim" personally challenged the legality of his continued detention today to the Court of Appeal in Wellington via a video link from Christchurch.
Stewart Murray Wilson, now 62, was jailed for 21 years in 1996 for rape, attempted rape, indecent assault, stupefying, bestiality and wilful ill-treatment of a child.
He was initially due to be released last month, but the Corrections Department filed an application for an order under section 107 of the Parole Act for him to be detained in custody until at least his applicable release date of September 2012.
The Parole Board agreed to keep him locked up after deciding he posed a risk of re-offending.
Wilson last month went to the High Court in Christchurch to challenge the decision, but the court ruled against him.
After winning an Appeal Court hearing, he today argued the High Court had been under pressure to make a fast decision on the issue.
He challenged points raised in a Parole Board report and claimed he had in effect been "re-judged and re-sentenced" when, in accordance with sentencing laws, he should have legally been able to walk free last month.
The Crown argued the High Court decision was in accordance with the law, while the Appeal Court justices queried some of Wilson's arguments, and at times had to remind him to stick to the issue at hand.
A psychiatric report drafted before Wilson's release application said he had denied his offending, had refused treatment while in prison and had made contradictory statements.
Wilson said today the report was carried out under duress, as a police officer was present at the time and his privacy was breached.
He also claimed he had suffered as a result of Parole Board information on him being made available - and released - by media.
The Appeal Court justices reserved their decision but promised to give the case priority and release a decision as soon as possible.
