North & South magazine says an article by a man who shot and killed his father and five other people was written in consultation with his psychiatric care providers.
Stephen Anderson was found not guilty of murder and attempted murder after the Raurimu massacre in 1997, on the grounds of insanity.
He was released into the community last year and told the magazine he regrets the killings.
North & South editor Virginia Larson says Mr Anderson's mother was also consulted about the article.
The magazine says Mr Anderson will be paid a freelance contributor's fee of about $2500 if he sends an invoice.
In the article, Mr Anderson cites research that says a cannabis ingredient may have useful anti-psychotic properties.
Ms Larson says Mr Anderson's views are his own and not the magazine's.