Police say the convicted sex offender who admitted using false documents to work in six North Island primary schools told elaborate lies including that he had a twin brother.
Te Rito Henry Miki has pleaded guilty to seven charges of using false CVs and a birth certificate.
The 41-year-old has over 40 previous convictions including common assault and three counts of indecent assault on a boy aged 12 to 16.
Police say Miki used a different name to gain employment at a Tauranga school, and when confronted by the school's principal, blamed his previous convictions on a non-existent twin brother.
He also worked at a Rotorua school while its principal was overseas and quit before the headmaster returned, citing a bogus brain tumour as the reason.
The names of the schools remain suppressed; several are seeking permanent name suppression.
One of the schools is also seeking suppression of an alias Miki used.
He will be sentenced on 18 May.