Material from the wreckage of the Canterbury Television (CTV) building should not have been dumped in landfill before a full forensic examination had been carried out on the collapse, an expert has told the Canterbury Earthquakes Royal Commission.
Robin Shepherd, an international expert commissioned by the building's designer Alan Reay Consulting, was giving evidence to the inquiry hearing on Tuesday.
The inquiry is looking into the collapse and subsequent fire that killed 115 people in the CTV building, the deadliest collapse following last year's February 22 quake.
Mr Shepherd, who supervised Mr Reay himself in his university studies in the 1970s, was particularly critical that material had been dumped before full forensic examination had been carried out.
He said it was impossible to say what might be discovered but if the material had been left on site it would have been possible, for example, to determine which columns in the building had collapsed first.
The CTV material has been secured in a special "sensitive" area at a landfill following its demolition in May 2011, nearly three months after the quake.
It was released for removal after a government engineer had sifted through the site.
However, the commission's lawyer Mark Zarifeh obtained admissions from Mr Shepherd that he had not read all the expert witness reports, had not visited a landfill where material was dumped, and had relied on newspaper reports for some of his expert testimony.
Earlier in the hearing, Mr Reay acknowledged that computer discs containing important information on the building had been disposed of.
Although the lawyers assisting the Royal Commission into the causes of the collapse have reiterated that the hearing is not adversarial, Mr Reay was clearly uncomfortable at the tone and direction of questions.
On Tuesday, the hearing, into its fourth of eight scheduled weeks, was suspended until next week due to illness of one of the panel members.