Detective Sergeant Sam Bindon, of Kerikeri police, said police and firefighters were called to the Matauri Bay property just before 11pm on Thursday after a confrontation at the property with another local man.
No one had been injured in the fire but the house had been "completely annihilated".
Police put a scene guard in place overnight and carried out a thorough examination yesterday. The home owner was helping Detective Bill Dawson and specialist fire investigator Craig Bain as they searched for evidence as to how the fire started.
Police were also speaking to people in Matauri Bay who had witnessed the incident or knew how the fire started. They were looking for one man in particular to hear his account of what happened.
Anyone else with information was urged to call the Kerikeri police station on (09) 407 9211 and ask to speak to one of the CIB staff or leave a message.
Kaeo fire chief Lindsay Murray said the house was burning fiercely when the brigade arrived. The Kerikeri brigade sent a tanker and shuttled water from a nearby creek with the aid of a portable pump.
The Kaeo volunteers returned yesterday to continue dampening down the ashes and charred framing that remains.
Until they find a new home Mr Rapata and his family will be staying with his father on the neighbouring property. The single storey triboard pole house was built in 1989.