Officials, constrained by over-zealous privacy laws, can say little and it's left to people in the community - mums, dads, and schools - to find out, sometimes too late, if one is living near them, or has infiltrated their lives.
This issue is back in the spotlight because the Government is considering setting up a sex offenders register. At first glance, it's a good move, one that is long overdue.
But unfortunately it already appears our weak-willed justice leaders will come up hugely short in delivering something that provides real public protection.
Police Minister Anne Tolley says the proposed register would be kept private.
"It is not about vigilantism," she says.
"When you look at what overseas jurisdictions have found, it just means people use that register for other purposes, to hound some of these people, when in fact they might be living quite sensible lives, they might be managing it quite well, they might be posing quite little risk."
So it seems only officials will have access.
Labour is even weaker on the issue, with justice spokesman Charles Chauvel wanting to see evidence such a list is needed at all.
He says the minister needs to show there is a "significant public safety problem out there" where there are convicted recidivist sex offenders at large who pose a risk to public safety, and who need to be listed on some sort of confidential register that officials can have access to.
Unbelievable. Here we are, closer to getting a register to protect people, including children, and the very people elected to serve us, our politicians, are proving a disappointment.
I simply cannot agree with them.
In my view, sex offenders are among the lowest of the low.
They should lose all rights to privacy once convicted, unless there is suppression, and the public should have a right to know who they are at any time without having to rely on the media, which cannot cover all the cases.
Concerned members of the public should be able to find out if someone in their lives is a convicted sex offender. The media should also have the right to publish this information.
This is not about vigilantism; it's about protecting innocent people.
I'm sure there will be liberals out there who strongly disagree and feel some need to protect these offenders.
But these criminals should not have inflicted their vile crimes on their victims in the first place.
Public interest and rights must outweigh those of convicted offenders, even once they are free.
