The police say their investigation into the collapse of Christchurch's CTV Building during the 2011 earthquake will now not be completed until some time next year.
The building's collapse accounted for 115 of the 185 deaths in the February 22 earthquake but, so far, nobody has been held accountable.
In June, the police raided the offices of structural engineer Alan Reay, whose firm was linked to the collapse during the Royal Commission into the disaster.
In September, the police said they hoped to complete their inquiry by the end of this year.
Today, they said a simmulated re-build and testing of the building's structure was taking longer than expected.
The investigation has been broadened to include other buildings that collapsed and killed people and 100 witnesses have been interviewed so far.