Auckland City Council blames the collapse of the Palace Hotel building in the city centre on the owners and those working on the building, and has raised the possibility of legal action.
The 124-year-old building in Victoria Street West was listed as a category 2 historic place, and became unstable in November. The council stepped in to demolish it because of safety concerns.
The council on Wednesday released a report on the collapse, which it says was caused by inadequate support of basement walls during renovations.
The council says the owners failed to do everything necessary to ensure the building was renovated safely, and site engineers and architects should have recognised the risk.
It says a council inspector visited the building the day before the collapse and called a halt to work.
It says its report has been referred to the Crown solicitor for advice on possible prosecution action.
The report has been forwarded to the relevant professional bodies for review, and a bill for council costs has been sent to the owners.
The building was demolished a day after cracks appeared and it began to move.
The developer, the Chow Group, said at the time that the council acted too hastily with demolition.