The family of Whakaari / White Island tour guide Hayden Marshall-Inman, 40, are not giving up hope his body will be found, as they prepare a service to celebrate his life.

Police Deputy Commissioner Mike Clement said today it was his strong belief Marshall-Inman's body, along with that of 17-year-old Australian tourist Winona Langford, had been washed off the island and out to sea in a downpour overnight on December 9, the day of the eruption.

Clement said a body, believed to be Marshall-Inman, was seen in the water near the jetty on December 11, but the Deodar police boat could not get close enough to recover it. Subsequent searches of the wider area had not been successful.

The search will now be scaled back, turning from a national-led operation to a regional one, though resources would still be available as needed.

Marshall-Inman's brother, Mark Inman of Ōhope, said that would not change anything for the family.

Hayden Marshall-Inman from Whakatāne was a White Island guide and died in the eruption. Photo / Supplied

"We are still positive and forever hopeful. You've got to stay that way.

"There are still two bodies out there, one of them being my brother and the other one being Winona.

"As long as there are still people out there looking it makes a difference."

Whether the two would be recovered was "in the hands of Tangaroa", he said.

"We will leave it for him to decide."

Inman's feelings have not changed about the first efforts to save all of those trapped on the island when it erupted, despite not having his brother back yet.

"I guess it was just those final few minutes of the initial response that may or may not have made a difference. But you've also got to remember too that authorities have got systems in place to protect others.

It is believed that the two remaining bodies of people killed in the White Island eruption have been washed out to sea, say police.

"You've got to trust in the process. Whether you agree with it or not, you've got to trust in the process."

He said communication from police had been good since Clement came on board, and he had no doubt that would continue when the operation was led from the Bay of Plenty.

"The local boys are magic. They will certainly look after us for sure."

Asked about Clement's comment that police did not discourage private aerial searches, Inman said that was normal after an event like this.

"We would go up every day if we could".

He said he had wanted to join the search since the first day - not only for his brother but for all of those initially left on the island.

"Its about getting all eight bodies home. That's been the feeling amongst the whole community. We saw that on day dot with the helicopter pilots and White Island crew."

Winona Langford was visiting White Island with her Sydney family when the volcano erupted. Only her brother Jesse survived. Photo / Supplied

The family had been humbled by the support from the Whakatāne community and beyond.

"We're forever grateful for all of the efforts ..."

A celebration of Marshall-Inman's life will be held on Friday.

"Until we get some closure it will always be a celebration of life," Inman said.

The event will be open to anyone whose life was touched by his brother, he said.

"Hayden touched many hearts around the world.

"To be able to share the stories with his friends and family and anyone else who he touched around the world - its going to be a truly special day."