A serial rapist diagnosed with sexual sadism disorder will be supervised for two years to prevent reoffending in the community.

Kerubee Bernabao Kalaw was convicted of sexual assault in 2006 and released after more than 16 years behind bars in May 2021 under strict parole conditions including wearing an electronic tracking device.

On Thursday, the NSW Supreme Court released its reasons for imposing a further two-year extended supervision order on Kalaw to reduce the risk of reoffending and assist with his re-entry into public life.

The ESO was granted by Justice Mark Ierace on December 12 last year with the judge finding the released inmate had made "encouraging" progress in the community and posed a relatively lower risk.

However, he noted that Kalaw had raped four women and threatened another in what were serious offences.

A diagnosis of sexual sadism disorder which was not yet in remission also led the judge to conclude that any reoffending would be "extremely serious".

"Accordingly, I was satisfied to a high degree of probability that (Kalaw) poses an unacceptable risk of committing a serious offence if not kept under supervision by way of an ESO," the judge said.

A report by forensic psychologist Dr Chelsey Dewson found Kalaw's "feelings of loneliness and inadequacy from his marriage" led him to a number of extra-marital affairs, including with sex workers, where he played a dominant role.

"These activities were considered to be sadomasochistic in nature, intensifying his interest in sexual sadism. He devalued the women involved and introduced more violent elements such as toy knives and guns," Justice Ierace wrote.

"In the three months prior to the index offences, his behaviour escalated to include non-consensual aspects to his activities with sex workers. Eventually he wanted 'the real thing'."

First arrested in October 2004, Kalaw was charged with more than seven sexual assaults that occurred while he was married.

In July 2006, he pleaded guilty to one count of threatening actual bodily harm with intent to have sexual intercourse, five counts of aggravated sexual intercourse without consent, and one count of maliciously inflicting actual bodily harm with intent to have sexual intercourse.

His victims were a 19-year-old threatened with a knife at a public payphone, a 17-year-old and a 42-year-old who were both sexually assaulted in his car after accepting a lift, and a 17-year-old and a 20-year-old who were both dragged into the bushes while walking home.

In September 2006, Kalaw was sentenced in Coffs Harbour District Court to a maximum sentence of 18 years and a non-parole period of 14 years, expiring on October 3, 2018.

He was assaulted several times while in prison, including being stabbed in his cell by an inmate influenced by a culture of attacking sex offenders.

Shortly after this, he was diagnosed with schizophrenia.

When his non-parole period expired, Kalaw was not released as he had yet to complete a sex offender program and was seen as unsuitable for community-based treatment.

Conditions of his ESO include that he inform corrective services of his weekly movements, wear an electronic tracking device for at least a month, avoid seeing sex workers without permission, and get psychological treatment for his schizophrenia.