A a group of concerned mothers tipped off police about an Auckland teacher's alleged sexual abuse of a student, it has been revealed.
Radio New Zealand has obtained documents detailing the Crown's case against Nicholas Baldwin, 61, who faces 17 related charges.
It says the abuse began in 2006 when the boy was aged 10 and lasted until late last year.
The victim and his school have been granted name suppression.
Evidence handed up at a deposition hearing states that three mothers with children at the school noticed Mr Baldwin and the boy together after hours and became suspicious.
They decided to follow Mr Baldwin and the boy, taking covert pictures and film footage of them allegedly kissing and engaging in sexual activity behind a park toilet block.
Mr Baldwin denies all charges, but his lawyer has conceded there is a prima facie case to answer.