Waxman also released testimony from former AIG auditor Joseph St. Denis, who resigned after being blocked from giving his input on how the firm estimated its liabilities.

Three former AIG executives were summoned to appear before the hearing. One of them, Maurice "Hank" Greenberg — who ran AIG for 38 years until 2005 — canceled his appearance citing illness but submitted prepared testimony. In it, he blamed the company's financial woes on his successors, former CEOs Martin Sullivan and Robert Willumstad.

"When I left AIG, the company operated in 130 countries and employed approximately 92,000 people," Greenberg said. "Today, the company we built up over almost four decades has been virtually destroyed."

Sullivan and Willumstad, in turn, cast much of the blame on accounting rules that forced AIG to take tens of billions of dollars in losses stemming from exposure to toxic mortgage-related securities.

Lawmakers also upbraided Sullivan, who ran the firm from 2005 until June of this year, for urging AIG's board of directors to waive pay guidelines to win a $5 million bonus for 2007 — even as the company lost $5 billion in the 4th quarter of that year. Sullivan countered that he was mainly concerned with helping other senior executives.

Sullivan also came under fire for reassuring shareholders about the health of the company last December, just days after its auditor, Pricewaterhouse Cooper, warned of him that AIG was displaying "material weakness" in its huge exposure to potential losses from insuring mortgage-related securities.

AIG's problems did not come from its traditional insurance subsidiaries, which remain healthy, but instead from its financial services operations, primarily its insurance of mortgage-backed securities and other risky debt against default. Government officials feared a panic might occur if AIG couldn't make good on its promise to cover losses on the securities; investors feared the consequences would pose a threat to the U.S. financial system, which led to the government bailout.

AIG suffered huge losses when its credit rating was cut, thanks largely to complex financial transactions known as "credit default swaps." AIG was a major seller of the swaps, which are a form of insurance, though they are not regulated that way.

The swap contracts promise payment to investors in mortgage bonds in the event of a default. AIG has been forced to raise billions of dollars in collateral to back up those guarantees.

Sullivan said many of the firm's problems stemmed from "mark to market" accounting rules mandating that its positions guaranteeing troubled mortgage securities be carried as tens of billions of dollars in losses on its balance sheet.