Two Transport Accident Investigation Commission investigators are in Auckland gathering evidence into the Kaipara Harbour fishing boat tragedy.
The Commission has been monitoring the police response to the tragedy and liaising with the police to obtain the necessary information to inform their investigation.
Chief investigator, captain Tim Burfoot, said it was early days in the investigation.
"We have a great deal of work to do but a lot of useful information has already been gathered. The local people and the police have been very helpful."
Meanwhile, police continued their search for last man missing from the capsized Francie today.
Police 4WD vehicles searched the Muriwai and South Head shoreline, collecting items and debris believed to be from the wreckage.
The Police Eagle Helicopter had begun wider aerial searches.
The Francie was yet to be located and specialist maritime police staff had been called in to help search for the vessel.
Two Commission investigators will be on the ground in the Auckland area for much of this week. They will be joined by two other investigators to assist with interviews and the initial gathering of evidence.
"There are a number of people we need to interview. We also need to work around the family arrangements for those who lost their lives in this tragic accident. This is not an easy time for those families," Burfoot said.
The Commission's inquiry will go through a number of stages including the gathering of evidence, analysis, the preparation of a draft report and publication of a final report.
"Any safety issues identified in the early phases of the inquiry can be addressed through urgent safety recommendations at any stage. It's too early to say whether the Commission is likely to consider doing this prior to issuing its final report," Burfoot said.
The role of the Commission is to determine the circumstances and causes of accidents and incidents with a view to avoiding similar occurrences in the future.
Eleven men were thrown into the rough seas when the Francie fishing charter capsized on Saturday afternoon.
Three survived, seven bodies have been recovered from the ocean and one is still missing.
Police were expected to release the victims' names and photos this afternoon.
Waitemata Inspector Mark Fergus said police were in regular contact with the missing man's family.
"They are coping as well as can be expected but are understandably wanting to get their loved one home."