Demolition is set to be completed today on the remains of a century-old Wellington building, but the cause of the fire will remain a mystery.
In a statement, police say they finished the scene assessment at the site of the Abel Smith Street building last night.
"We have been unable to determine the cause of the fire and the building has been returned back to its owners," the statement said.
A police spokesperson confirmed to RNZ the investigation has been closed, saying "there is no further police involvement".
The building, which was razed by fire on Tuesday, had to be demolished before it was safe for investigators to enter as it was structurally unsafe.
The Lebanese Society, which owns the house, said the collapsed building was deemed a public health risk.
Society secretary Stephen Wakem said seeing the 120-year-old building torn down was tough, particularly as there were plans to restore it and use it as a hub once again.
"It is a hollow feeling to think that the building - it's partially demolished at the moment - is going to be gone by the end of today perhaps."
The two-storey building was used for decades by community groups and known as 'the anarchist house'.
"It is a strange feeling of loss - what it represented and what it was symbolic of," Wakem said.
He said "there has been a lot of reminiscing" about the significance of the building, and the Lebanese community would come together formally to commemorate it.
Police had told him they had been unable to determine where the fire began, Wakem said.
"It's really unknown whether there was anyone inside or not [to start the fire], whether it was an external blaze or started internally. We have no information based on what the police have gathered so far."