A man who murdered a British backpacker in 1989 has been denied parole because he is "at serious risk of criminal behaviour".
Monica Cantwell, 24, was walking on a track near the summit of Mt Maunganui in November 1989 when Charles John Coulam grabbed her, dragged her into the bushes and raped her.
He strangled her during the attack and left her lying semi-naked about 50m from the track.
Parole denied but killer walks streets
Her body was found three days later after her worried friends reported her missing.
Coulam was arrested and charged with murder soon after. He was sentenced to life imprisonment.
In 1996, Coulam was diagnosed with schizophrenia and transferred from prison to a mental health facility.
A court order made Coulam a special patient under the Mental Health Act, meaning he must remain in a secure mental health facility indefinitely.
He became eligible for parole in 2011 but was refused on the basis that he still posed a risk to public safety.
On September 8 Coulam appeared before the Parole Board and was denied an early release again.
The board's decision, released to the Herald, revealed that Coulam's mental disorder is "treatment resistant".
"In addition there is an overlay of an excessive compulsive disorder with elements of sexual sadism and autism spectrum," it said.
Coulam's "psychotic symptoms" were said to be under control with medication and the board said he was making "good progress".
"He has had a significant number of unescorted community outings and is on a second week of a computer course.
"It is clear he could not possibly manage at present in the community, as [he] is at serious risk of criminal behaviour.
"Parole is declined and he will be seen again in a year's time."