Concerns about a Far North teacher who this week admitted sexually abusing pupils were first raised with police 16 years ago.
James Parker, 37, who was the deputy principal of Kaitaia's Pamapuria School when he was arrested last month, admitted 49 charges of sexual offending involving around a dozen boys aged 11 to 13.
Most of the charges related to offending since 2009, but police are continuing to investigate whether there are more victims, and Parker could face further charges.
A former principal who employed Parker when he was in his early 20s told Radio New Zealand she had raised concerns with police about him 16 years ago.
She said Parker had pupils of a poorer school - whose stressed parents needed a break - stay at his house for sleepovers, and he would share his bed or tent with pupils on school trips.
A former flatmate of Parker's backed up claims he would sleep in the same room as children at the house.
Detective Inspector Karyn Malthus confirmed police are now investigating claims dating back several years.
She said Parker and the students allegedly involved in earlier incidents were interviewed but "the matter could not be substantiated", rejecting suggestions of inaction by police.
Parker was also the subject of an investigation by police, the Ministry of Education and Child Youth and Family (CYF) in 2009, which again resulted in no charges being laid.
Teachers Council director Peter Lind told NZ Newswire the council wasn't informed by either the school or police of the 2009 investigations.
It was "absolutely critical" such information was passed on - one of the key recommendations following a recent investigation into how a convicted child sex offender, Te Rito Miki, was able to work at a number of schools because of impediments to sharing information.
Pamapuria School's board of trustees resigned after learning of Parker's sexual abuse, and a commissioner, Larry Forbes, has been appointed.