The SEC brought a civil case in which Mozilo agreed to pay $67.5 million over claims he misled investors about the firm's exposure to risky loans.

They Looked

"It's not because we didn't look" at cases related to the crisis, said Kevin Perkins, the FBI's assistant director overseeing criminal investigations. "If the case is there and it can be made, we're going to do that."

The Justice Department has trumpeted other cases involving insider trading, stock manipulation and Ponzi schemes.

Lee Farkas, the ex-chairman of Taylor, Bean & Whitaker Mortgage Corp., was found guilty on April 19 of what prosecutors said was a $3 billion scheme involving fake mortgage assets that duped financial institutions and contributed to the failure of Montgomery, Alabama-based Colonial Bank.

Losing Agents

Former prosecutors said one reason for the decline in the fraud prosecutions since 2003 may be that FBI agents were reassigned after the Sept. 11 attacks from criminal cases to national security. In recent years, the FBI has boosted the number of investigators of white-collar crime, Perkins said. An average of 106 agents were working on corporate fraud cases last fiscal year, up from 88 in 2008; 219 worked on securities fraud, up from 150 in 2008, Perkins said.

Still, the prosecution of 131 defendants for corporate fraud in the year ended Sept. 30 was down 58 percent from 2003, the first year the Justice Department tracked the cases. There were 250 securities fraud prosecutions, down 16 percent from 2003. For bank fraud and embezzlement, prosecutions declined steadily, with 1,515 last year, down 39 percent from 2003.

In mortgage fraud, the department pursued 1,197 prosecutions last fiscal year, up from 492 the year before.

"The recent financial crisis is different from what occurred in 2003," said Robb Adkins, executive director of a financial fraud task force announced in 2009, when Holder pledged the crackdown. "The crisis was multifaceted, and the types of financial crimes that furthered or preyed upon the crisis are broad."