Published: Apr 05, 2010 5:59 PM EDT

WASHINGTON (AP) — A panel investigating the roots of the financial crisis is preparing to press current and former executives of Citigroup Inc. about the bank's role in spreading trillions of dollars in risky mortgage debt through the banking system.

The Financial Crisis Inquiry Commission on Wednesday and Thursday is holding its first hearings focused on a single company. Citi CEO Chuck Prince and former Chairman Robert Rubin are among the witnesses.

The agenda also includes testimony from former Federal Reserve Chairman Alan Greenspan and executives and regulators from government-backed mortgage giant Fannie Mae.

The three days of testimony are designed to provide a firsthand accounting of decisions that inflated the mortgage bubble and triggered the financial crisis.