Police say their investigation into the collapse of the CTV building in Christchurch in last February's earthquake, will be unprecedented in terms of complexity and will involve an enormous amount of work.
A Government report says engineers found its main supporting walls and columns did not meet proper standards when it was built 26 years ago.
The report has been given to the police, who will decide if charges should be laid.
One hundred and fifteen people died when the building collapsed on 22 February.
Assistant Commissioner Malcolm Burgess says the case is technical and complex and will involve an enormous amount of work.
Police will assess the report by the Department of Building & Housing before deciding whether any charges will be laid.
The building housed Canterbury Television, a nurse training school, a medical centre, Relationship Services and King's language school.