Grove is straight with them; he and his squad are not the offender's buddies, the police will prosecute any criminal admission they make. But it is clear that these child sex offenders sense a change in the tenor of this relationship with the law. The way they see it, Operation Guardian is there to protect them - albeit from themselves.
It's a very special copper who can take on this job. Officers have to sublimate personal feelings and give these abusers the kind of respect they never accorded their victims. Operation Guardian officers need the right experience and aptitude to build relationships of trust with these, the most taboo members in our society. Because they are in our society. Once any offender has done their time, they have to adjust to life among us.
The two clients I met are in halfway houses, both of which are owned and managed by the Seventh Day Adventists. There are a number of rules to live by and most are required to attend daily Bible classes. Redemptive or not, the daily schedule and orderliness of a well-managed house must be helpful to institutionalised ex-cons trying to stay on the straight and narrow. God only knows what they'd do with too much time on their hands.
Grove says boredom and isolation are the two gravest dangers for a child sex offender who is trying to stay "sober", (my word, not his). Conditions of their release may involve a radical family-ectomy - a mandatory cutting off from one's offspring.
"I don't see why they won't let me see my baby daughter. I only do boys, so what's the problem? Even if I did girls, it wouldn't happen till she was like 7, so what's the problem?"
This is the logic of J, whose girlfriend has just given birth. "But you're not going to see your girlfriend even if she tries to contact you, are you? Are you?" Grove asks, his eyes are fixed and penetrating. He is making sure the full weight of the question lands. J concedes that that would be a very stupid move indeed. It's pretty clear that J regards Grove as his best chance to stay out of prison. And this is his overriding concern. One of the conditions of J's release is that he never be in the company of children. He says he typically started grooming kids at 4 and sexually assaulting them about 5. He says that if he has access to a kid, he is 100 per cent likely to molest, so powerful is the compulsion.
A few months ago, a panicked J rang Operation Guardian. "Help. A guy just moved in here with a 4-year-old son. I'm gonna get arrested!' Grove made sure J was pulled out of the house immediately. That's a result right there.
The second man we visited, O, is a completely different kettle of fish. He's a good talker, petulant and without insight into his condition. Unlike J, O has done no child sex offender therapy courses in prison. It's a red flag for our detectives. He has no interest in rehabilitation. In fact, neither man seemed to have any care for the kids they abused or may yet abuse, but they really, really don't want to be sent back to jail. It's all about them.
Shocking to me is that both these guys are only halfway up Operation Guardian's list of 80-Likeliest-to-Re-Offend.
This is the point where most of us switch off and vow to keep our own kids safe from predators, but switching off is not an option for these police officers.
And it comes at some cost to themselves. They tell me their own children complain about having overly-protective parents but they just can't leave lessons in human darkness at the office.
The Child Exploitation Team's strategy is to rotate officers every 8 to 12 months to keep them functioning optimally. The pressure to get it right is enormous. No one knows how to stop the recidivist paedophile but Operation Guardian is yielding good results in actual prevention. I came away enormously grateful to Counties Manukau Police for having the wherewithal to realise the next best idea.