User:Cs32en/911/Sources/Daily News/Shin/2002-03-07/content

"[...] About 80% of the structural steel from the World Trade Center was scrapped without being examined by even one fire expert, mostly because investigators did not have the authority to preserve the wreckage as evidence, the experts said.

"The lack of significant amounts of steel for examination will make it difficult, if not impossible, to make a definitive statement as to the specific cause and chronology of the collapse," said Glenn Corbett, a fire science expert from John Jay College of Criminal Justice in Manhattan who testified before a House Science Committee inquiry into the collapse and the ensuing investigation. [...]

The lead investigator in the case, Gene Corley of the American Society of Civil Engineers, said the Port Authority refused to hand over blueprints for the twin towers - crucial for evaluating the wreckage - until he signed a waiver saying his team would not use the plans in a lawsuit against the agency."