Mr. Mozilo’s up-by-the-bootstraps background and entrepreneurial success earned him accolades and outsize pay during the mortgage industry’s heyday. But he became a lightning rod for criticism in 2007 when subprime loans started to go bad and foreclosures escalated.

Image Angelo R. Mozilo, then the chief executive officer of Countrywide Financial Corporation, testifying on Capitol Hill in March 2008. Credit... Jay Mallin/Bloomberg News

The S.E.C. brought its case against the former Countrywide officials on its own; Justice Department officials did not file criminal charges simultaneously with the commission, as is often the case. But a securities law expert said this did not guarantee that Mr. Mozilo and his former colleagues were clear of being charged by criminal authorities.

“It could mean that the Justice Department does not yet have a case proving the highest standard, beyond a reasonable doubt,” said Lewis D. Lowenfels, at Tolins & Lowenfels in New York. “They may want to see what facts come out in the discovery in the S.E.C. case and there might be other people they are interested in. Moreover, the S.E.C. is under so much pressure from Congress, they may want to move quickly and not wait for anybody.”

Among the e-mail messages written by Mr. Mozilo and cited by the S.E.C. was one from April 13, 2006. In it, Mr. Mozilo told Mr. Sambol and Mr. Sieracki that loans had been written by the company without regard for its processes and guidelines. He went on to describe as “poison” subprime second mortgages, a product from Countrywide that required no down payment from a borrower.

In another e-mail message, Mr. Mozilo discussed a type of mortgage known as a Pay Option adjustable-rate loan. This was one of the so-called affordability products that let borrowers pay a fraction of what they owed in principal and interest each month.

“We have no way, with any reasonable certainty, to assess the real risk of holding these loans on our balance sheet,” Mr. Mozilo wrote. “The bottom line is that we are flying blind on how these loans will perform in a stressed environment of higher unemployment, reduced values and slowing home sales.”