How can I get a criminal background check?

[globetrotter]

[Apologies to any regulars for posting this in two forums, but I just wanted to cover my bases.]

Hi all... I'm sure this is an atypical question for these forums, but hopefully someone can guide me in the right direction.

I'm moving abroad in January and hoping to get a job working in a school in New Zealand. I've worked in schools before, but I doubt I'll be able to land a job working with kids if I don't have legal proof that I have no criminal record.

I live in California, by the way. Is there some state (or, even better, national) agency I can contact to get something like this? Any idea how much this will cost me and/or how long it will take to process?

Any replies appreciated!