Bid in NSW Supreme Court to stop release of Wayne Lindsay Wilmot involved in Janine Balding's murder

It comes as the offender, Wayne Lindsay Wilmot, 46, is due to be released this month after serving a 20-year jail term for other kidnapping and sexual assaults against multiple victims.

The Supreme Court held a three-day hearing this week after NSW Crown advocate David Kell, SC, applied for a two-year continuing detention order on Wilmot.

Wilmot was one of five homeless young people who abducted 20-year-old Ms Balding at knifepoint near Sutherland railway station in 1988.

Ms Balding, who was working as a bank teller in Sydney, was taken to a park where she was raped and murdered.

Wilmot was given a lesser sentence for kidnapping and assault then released in 1998 for a short period before being jailed again.

Ms Balding's brother, David Balding, said Wilmot being detained for longer is "better than him being out".

He said "they've got to do whatever they can to keep him in" because he has concerns Wilmot may reoffend.

"He was only out for a short time in 1998 [before being jailed again for other offences]."

Mr Balding, who still lives in Wagga, said he and the family is going as well as they can.

Victims advocate Howard Brown, who was in court, said the hearing centred on whether a continuing detention order or extended supervision order should be imposed.

"Wilmot has a history of offending so substantial that you'd think a reasonable person would come to the view that the community can't be protected unless he's detained," Mr Brown said.

"The trip from Sutherland railway to where she was murdered would've been the most terrifying experience. She would've done all she could to preserve her life."

He said the extended supervision order applied for was five years.

"It strikes me that there'd be a great deal with supervision for Mr Wilmot in the community ... hopefully that would strengthen our case for a detention order" he said.

Justice Julia Lonergan has reserved her decision until later this month.