"The family believe that if [the teen] is exposed in the [Tasman] area it's almost certain they'd have to leave the area where they've lived most of their lives."

Ok, fair. But then "The teen pleaded guilty to the charges in Nelson District Court in October last year after spending eight months in a secure facility."

It will be hard for the family to explain that time away so people around the teen's school and social circles will pretty much know.

Plus, Tasman is a pretty sparsely populated area. My Dad used to live in Nelson, and I went to Golden Bay/Takaka quite a bit.

gzt: Article states the firearms licence was valid for the shotgun. Licence was not valid for the AR-15. I'd like to know how the AR-15 was obtained. The article does not cover that aspect.

Quite possibly bought prior to the ban on them then they were never handed in.

Varkk:

 

Quite possibly bought prior to the ban on them then they were never handed in.

 

Lots of people didn't hand them back.  Polcie estimate ranged from 56,000 - 240,000 MSSAs.  A total of 56,250 firearms were handed in, some of which were not MSSAs.

People being people, it didn't take long for the info about what people were getting for common types of rifles.

I know anecdotally of criminals being offered a multiple of what the police were paying.

My conclusions: some (?most?) MSSAs were surrendered, some were not, some were retained, it's likely some were illegally sold to nefarious characters.  

Disclosure: I'm a keen hunter and have owned at times up to a dozen firearms (different tools for different tasks).  I have never owned an MSSA, never wanted to.