Expatriate New Zealander Robert Murray Wilkinson, 64, was fighting for his life after being attacked while investigating a disturbance at popular holiday spot Waihi Beach about 1am on January 1.
But the Queensland resident died in Waikato Hospital's intensive care unit today.
Thirty police staff were now working on the homicide investigation as they hunt for the attacker, who fled the scene when neighbours heard a disturbance.
The weapon had not yet been found, and police were asking witnesses to come forward.
Checkpoints were set up at Waihi exit-points yesterday for police to talk to holidaymakers as they left the area.
Police have also asked New Year's Eve partygoers to supply their festive photographs, in the hope the pictures identify the attacker.
"It's the people who may be in the background or off to the side [of the photos] we're interested in.
"If you took images between 12.30am-1am on Tuesday morning around where Mr Wilkinson was attacked, please send them to Thames@police.govt.nz with the names of whoever you can identify in the picture,'' Detective Inspector Chris Page said.
Inspector Dana McDonald said given the advantages of modern technology it wasn't inconceivable that with the public behind them, police could identify through images provided from the public, the majority of people present in the area around the time of the attack.
Mr Page appealed to the attacker to give himself up.
"This matter is now a homicide investigation and can be resolved by the persons involved making contact with us or our team locating them. We ask that if you know who was involved or were involved you make contact with police.''
A forensic examination of the scene was completed yesterday, and a scene examination was continuing.
A post mortem examination of Mr Wilkinson's body would be completed in Auckland tomorrow.
The 'Operation Brad' police investigation continued today, with Waikato police being joined by colleagues from neighbouring districts to allow the net to be cast wider.
Officers who had been canvassing the area for a weapon for the past three days were now carrying out various area searches.
Waihi Beach's normal population is about 3000 but swelled to 16,000 over the festive period.
When the attack occurred, officers were moving on large numbers of mostly young people from the area around the surf club, the motor camp, Beach Rd and Ocean View Rd.
Information for the Operation Brad investigation could be left with police on 07 858 6200 or anonymously with Crimestoppers on 0800 555 111.
