A mental health expert has no qualms with a mass killer being employed in an arts school that had no knowledge of his past.

Stephen Anderson killed six people, including his father, in a rampage back in 1997, but was found not guilty by way of insanity.

He's now working at Wellington's Inverlochy Art School, where the principal had no idea about his history.

Mental Health Foundation chief executive Judi Clements says he'll be very carefully managed.

"This isn't a haphazard approach in that they're some of the most carefully monitored people we'll ever have in our community."