Tens of thousands of WTC occupants and visitors were exposed to 1,500 times the safe levels of caesium-137 on a daily basis for years. The steel was deliberately contaminated by union steel workers on the payrolls of organized crime. Instead of properly disposing of radioactive waste, they tossed it into cement bridge pilings, sporting parks, and in this particular case, the mill cauldrons used to make the steel for the WTC.
There was no actual lethal intent. The steel workers on the take knew where the steel would be used. They thought melting the caesium-137 would "dilute" it sufficiently to be harmless, it was simply a convenient disposal issue. Or so they thought.
The radioactive contamination was discovered and kept secret by two separate insurance companies, who then conspired with the building management, owners, and the New York Attorney General to conceal it. One of those companies was AIG.
The radiation poisoning of thousands of innocent people had to be covered up for liability and legal purposes. A diabolical plan to destroy the buildings and remove the debris evidence was concocted.
AIG would shoulder the lion's share of the financial costs and cover all human associated liabilities, provided they were "reimbursed". The administration of William Jefferson Clinton became aware of the planning and demanded blackmail money to close their eyes. They then decided to participate in the crime. This drove up costs exponentially and delayed the plan execution for nearly a year while the money was covertly distributed and various witnesses silenced.
By this time, AIG was nearing financial insolvency and banks were beginning to ask questions. A federal promise of funding ended the concernes of the financial institutions involved.
The money to AIG had to be disguised. A hurricane wasn't enough. Some banks had to be sacrificed to misdirect the focus of the general public. A false financial crisis was constructed. There was much disagreement over which banks would fail and how much the total of the payout would be.
The Bush administration wanted those involved prosecuted and jailed for crimes against humanity. Wall Street convinced them that the resultant publicity could destroy the financial bedrock of the United States. The bickering continued for years. The Bush administration gave in during 2007 and demanded that loose ends be tied up and accounts settled.
Thus began the great fraud known as TARP. TARP, the fraud that Barack Obama picked up, saw that he could manipulate it to his advantage and did so. AIG got their money and escaped, so did all the others.
In the meantime, all the contaminated evidence went to Chinese steel smelters, who never once thought to check the material for radioactivity.