The families of the 29 men who died in the Pike River mine explosions are carrying out their own investigation to try to establish what sparked the tragedy.
Spokesperson Bernie Monk says they have complete faith in the Royal Commission to get to the bottom of the disaster, but they have reasons for conducting their own investigation.
Mr Monk says the purpose is to educate both their legal team and relatives unfamiliar with mining, about the industry.
He says their interviews will cover all aspects of the mine, including the consenting process, ventilation, safety and working conditions.
Mr Monk says the families want to be fully informed, so they have an authoritive voice at the Royal Commission.
Chief Coroner Neil MacLean declined to comment, as his own inquest will start on 27 January.