"It should be a concern for anyone near where he's going," former Corrimal detective sergeant Paul Cole said.

Mr Cole was a member of the taskforce created to track down the elusive rapist whose reign of terror swept Wollongong's northern suburbs in 1989 and 1990.

He believes there is a real risk that Williamson could pick up where he left off.

"He's only 42 now, he's going on 43 … so, I mean, he's still a young man," Mr Cole said.

"You just don't know."

Although hunted nightly by police on foot and road patrols, Williamson had a habit of returning to the same areas, and even the same streets, where he had attacked before.

"It was a game to him, it was a thrill," Mr Cole said.

"It was the thrill of the chase, of being chased by the police and escaping.

"He also had a very intense sex drive which he admitted he just couldn't help himself, he just had to go out there."

A 20-year-old Williamson kidnapped, raped and sexually assaulted 11 victims, including children as young as five.

Next Friday, he will discover whether his latest bid for freedom has been granted by the State Parole Board.

Every other application the former truck driver and labourer has made since 2004 has failed, but this time he has the backing of the independent Serious Offenders Review Council.

If this bid proves successful Williamson would likely be placed in a community offender support program which provides accommodation and supervision for offenders on parole, Victims of Crime Assistance League Inc NSW vice-president Howard Brown said.

Mr Brown said he anticipated Williamson would be subject to strict curfews and electronic monitoring, and also be banned from entering the Illawarra.

Although he would still be subject to some level of supervision should he remain in jail, Mr Brown said the level of supervision applied to sex offenders on parole was far stronger.

Williamson has also been taking anti-libidinal drugs to help suppress his sexual urges.

"In two years that parole is going to run out," Mr Cole said.

"If he has accepted that he has to take the medication while he's on parole, in two years' time he's only going to be 45 when it expires ... the parole board has got nothing over him anymore."

Mr Cole said the dilemma was that Williamson had served the bulk of his 24-year maximum sentence, a period longer than that handed down to some murderers, and would need to be released into the community at some point.