Infamous rapist Stewart Wilson, dubbed the Beast of Blenheim, is likely to be among the first paroled offenders to be tracked around the clock by satellite under changes announced by the Government.
After years of trials, the Corrections Department will introduce ankle bracelets with a global positioning system (GPS) for high-risk criminals released into the community.
Corrections Minister Anne Tolley said 11 child sex offenders already released from jail would be the first to be monitored in real time and around the clock, beginning in August.
If one of the offenders strayed into banned areas such as schools or parks, Corrections would be alerted.
Prisoners pending release were also expected to be monitored, including Wilson, 65, who yesterday pleaded for release to the Wellington High Court after 18 years in jail.
He was convicted in 1996 of 19 offences spanning 25 years, including rape, attempted rape, indecent assault, wilfully ill-treating a child and bestiality.
The Probation Service has applied to have Wilson put on extended supervision for more than a decade. He was expected to be released in September despite the Parole Board's belief that he would reoffend.
Under current law, Corrections were permitted to monitor offenders using whatever technology was at their disposal.
Mrs Tolley said the GPS locators would be extended to 90 people by the end of the year, including criminals who had been jailed for violent offences.
The scheme, which cost $750,000 a year, would be expanded to 200 offenders in the community by the end of 2013.
It was part of a larger Government programme in prisons and communities which aimed to reduce re-offending by 25 per cent by 2017.
Labour Party corrections spokesman Charles Chauvel said if the move increased public safety while reducing inmate numbers then he welcomed it.
But he felt it contrasted with the Government's radical proposal to lock up the worst offenders indefinitely.
"[Justice Minister] Judith Collins and [Prime Minister] John Key have made a big issue of locking up people that escape preventative detention.
"But if the technology is sufficient, then maybe it's worth looking to this sort of solution rather than spending $100,000 a year per offender to keep people locked up."
The Government announced in November that it planned to introduce legislation to allow the Parole Board to keep prisoners in jail indefinitely if they posed a high risk of sexual offending or violence. It was not expected to be passed before Wilson was released and would not apply retrospectively.
The Government has tested several GPS bracelets since 2005, with many considered too bulky or unreliable.
Offenders with GPS locators would have to charge their own ankle bracelet, and if the charge became low Corrections or police would be called to investigate.