A CCTV image police released during the appeal for information. Photo / NZ Police
During the search, Detective Inspector Scott Beard had said police were treating the case as "extremely serious" and called Robertson "dangerous".
Judge Dawson said Robertson was now subject to the three strikes law and accepted the Crown's application to move the sentencing to the jurisdiction of the High Court.
The motion was made by prosecutor Fiona Culliney so that the Crown could seek a sentence of preventive detention. Only a High Court could impose an indeterminate punishment.
It is not the first time Robertson has been convicted of serious sexual offending.
According to his Parole Board reports, Robertson served a 15-year prison sentence for rape, unlawful sexual connection and abduction with a sentence expiration date of July 25 2016.
He was released the month prior, subject to standard and special release conditions for six months.
Those conditions included an overnight curfew and required compliance with electronic monitoring.
Prior to his last term of imprisonment, Robertson was convicted of rape in 1983 and was sentenced to six years.
