A former girlfriend of the man known as the Beast of Blenheim said she is devastated he will be released next year, and he should never be allowed out of prison.
Stewart Wilson was convicted in 1996 on a raft of sex offences involving 16 females over a 23 year period and is due for release next September.
Lois Laneghan, who met Wilson through a dating agency, told Radio New Zealand it was the worst thing she could have done.
"He was abusive, he was sexually starved and that wasn't me. It made me sick, it turned my bloody stomach up," she said.
"I went to the court case and I was disappointed he only got 21 years, he should have got much longer."
A parole board review released yesterday said Wilson is four times more likely to re-offend sexually than the average rate, and he had "limited motivation to comply with the possible conditions of release."
Asked if he would comply with a condition that he not have any contact with a child under the age of 16, Wilson was reported to have said "I don't give a stuff about it".
Former police detective Colin Mckay, who led the investigation against Wilson, said he was concerned how the victims would react to his release.
"He was a very manipulative man, he took advantage of all of these people when a lot of them were at a very low point in their lives," he said.
"If he's not accepting his guilt I fear his release will be another dramatic time for those involved. (They will be) fearful he may take some sort of action or intimidation against them."
But Forensic Psychiatrist Dr Justin Barry-Walsh told TV ONE's Breakfast that Wilson's years in prison may have reduced his risk to society.
"Offenders like this have an enduring quality that means it's very difficult to turn them around or work with them," he said.
"But we also know, particularly with ageing, the risk of offending reduces and often some of the rougher edges of personality rubs off."
Wilson has been denied parole on previous occasions because of the risk of him reoffending, however the Parole Board said at this time it had no option but to release him next year as he has been kept in prison as long as possible.