"[We need] to find out whether the sale of the island followed the correct process so that we know whether that was legal."
Dover Samuels, former Te Tai Tokerau MP, said the island was extremely significant to the Matauri Bay-based hapu Ngati Kura.
"All the islands in the Cavalli group are important. Our interest is in the pa and burial grounds that are on those islands. Our hapu lived their in the 1800s," he said.
Mr Samuels said that in the early 1990s his hapu [Ngati Kura] formed a Maori trust, MahiMahi E5 Trust, and managed to buy the island but had to sell it soon after.
"When that came up to the Maori Land Court they advised we were not permitted to buy the land as it was not the purpose of the trust and said it was illegal. They said we weren't allowed the land and told us to sell it, and we did reluctantly. Why we listened to the judge when we had the chance to buy back a taonga, I don't know."
Mr Samuels said knowing the island was for sale again, despite the fact the sale to the current owners was still under investigation, was frustrating.
"Motukawaiti has been under questions for nearly five years - we've asked time and time again about the investigation and now it's on the market on an international site for $12 million."
Annelies McClure, manager of the Overseas Investment Office, Land Information New Zealand (LINZ) said the investigation was complex and involved a number of individuals.
"The OIO has sought, and continues to seek, specific information and documentation from various parties. We are unable to provide further detail or information, as this could impede the OIO's ongoing investigation."
Ms McClure also said it was legal to sell the property while the previous investigation was underway.
Mr Davis said he was committed to assisting Ngati Kura in the return of the island, while Mr Samuels said he hoped one day that return would happen.
"We would be absolutely appreciative [if the island was returned to Ngati Kura] but I'm not holding my breath," Mr Samuels said.
