But retired Corrimal detective sergeant Paul Cole said that two years under supervision might be better than if Williamson, 42, remained locked up until his 24-year maximum sentence ends in 2014.

The NSW Parole Authority yesterday granted the convicted rapist parole but imposed strict conditions, including electronic monitoring and a ban on visiting the Illawarra region.

"Maybe it's better that he's out for these two years where he's strictly controlled," Mr Cole said.

"Whereas, if he didn't get parole and [was] just released after another two years, there'd be no restrictions or anything left on him and he could go wherever he pleased."

Williamson terrorised Wollongong's northern suburbs in 1989 and 1990 in a crime spree that saw him rape and assault 11 victims, including a five-year-old girl.

Several parole applications have been rejected since he became eligible to apply for release in 2004.

Mr Cole said Williamson's age could be a cause for concern.

"To me, at 42 years old, he's still only a young man and anything could happen," he said.

The former detective remembers the fear Williamson caused in the community, the chatter about vigilante groups and the "extreme" pressure on police to get results.

He said he also remembered the man who caused such panic being an "unassuming sort of person".

"I mean, he was very quiet, he was very quietly spoken, he was well-mannered," Mr Cole said. "If you first met him back in 1989 and '90 you would not have suspected him."

He said the 24-year maximum term imposed was more than police at the time had expected.

Williamson is reportedly due to leave custody in Sydney between February 10 and 17.