Wayne Lindsay Wilmot, 46, was due to be released in June this year after serving a 20-year jail term for other kidnapping and sexual assault offences against multiple victims.

He then had an interim detention order placed on him that was renewed three times until September 25.

On Tuesday following a three-day hearing earlier this month, Justice Julia Lonergan granted an application by NSW Crown advocate David Kell, SC, to detain Wilmot for another two years.

Justice Lonergan said there was a high probability that Wilmot may commit a serious offence if he is not kept in detention because of his criminal history of repeated violent and sexual offending on young women.

"The offending seems often to be impulsive and sudden," Justice Lonergan said.

"It is evident that Mr Wilmot shows no insight into his offending. He has not even acknowledged - in the main - that the offending occurred at all despite trials resulting in convictions and one unsuccessful appeal."

Since Wilmot was 14 years old, he has spent most of his life in custody because of his criminal offences.

Justice Lonergan said he "victim blames in a shamelessly callous way" and that "he has not properly engaged with even the first step to rehabilitation".

"He is manipulative. He perseveres with a significantly warped view of social interaction with women and his imagined right to take, with force, whatever he decides he wants or to respond with aggression to whatever he does not like," she said.

Evidence tendered to the court included expert reports by forensic psychiatrist Dr Kerri Eagle.

Dr Eagle diagnosis found that Wilmot showed a number of psychopathic traits, including lack of remorse or guilt, promiscuous sexual behaviour and failure to accept responsibility for his own actions.

Lawyers representing Wilmot argued that the criteria for a detention order had not been met.

However, Justice Lonergan said she found the plaintiff's arguments "ultimately persuasive and well founded on the evidence".

"While the defendant's psychiatric and social background are most unfortunate and not irrelevant, what they illustrate is some of the reasons why the defendant is likely to seriously re-offend and how difficult these matters are now to manage and treat," she said.

Wilmot's extensive criminal history includes serving eight years for the abduction and rape of Ms Balding in 1988.

The 20-year-old bank teller was grabbed from a Sydney train station by five homeless youths before she was repeatedly raped then murdered.

Wilmot's detention order will expire on September 23, 2021. The plaintiff's application also included a five-year extended supervision after the detention order.

However, Justice Lonergan declined to make that order, saying she was unable to predict what will be suitable for Wilmot in two years.