But the previously confidential documents raise questions about the bank’s decision to fight, rather than settle, cases filed by plaintiffs including the Federal Housing Finance Agency and the New York attorney general. In its lawsuit against Credit Suisse, the F.H.F.A. is asking for damages relating to $14 billion in mortgage securities purchased from the bank by Fannie Mae and Freddie Mac, the government-sponsored mortgage giants.

Image Credit... Shannon Stapleton/Reuters

The New York attorney general’s case is seeking $11.2 billion to cover losses incurred by investors in the state who bought mortgage securities from Credit Suisse. Credit Suisse has argued that the New York case was filed too late and has asked the court to dismiss it.

During the housing boom, Credit Suisse was a fairly big player, bundling $203 billion worth of mortgages into securities that it sold to private investors between 2005 and 2007. By comparison, Countrywide Financial, a more prominent mortgage lender, sold $277 billion of those securities during that period.

But Credit Suisse was not as well known in the mortgage business as its Wall Street rivals like Bear Stearns, Lehman Brothers and Merrill Lynch. And in the aftermath of the crisis, Credit Suisse was not as closely scrutinized by congressional investigators and securities regulators plumbing the origins of the debacle.

But the Swiss bank has come under the microscope in recent months. In late February, four of its top executives, including Mr. Dougan, testified before Congress about the bank’s involvement in helping United States citizens hide money overseas and avoid taxes. Mr. Dougan contended that only a handful of bank employees were involved in the questionable activities and that Credit Suisse had improved its compliance. And last year Kareem Serageldin, a former mortgage trader at Credit Suisse, was found guilty of hiding more than $100 million in mortgage bond losses at the bank by inflating the bonds’ value as the housing market collapsed. He was sentenced to two and a half years in prison.

At Mr. Serageldin’s sentencing hearing last November, Judge Alvin K. Hellerstein of the United States District Court in Manhattan, criticized the culture at Credit Suisse. “He was in a place where there was a climate for him to do what he did,” the judge said of Mr. Serageldin. “It was a small piece of an overall evil climate inside that bank and many other banks.”

Credit Suisse officials objected to the judge’s characterization at the time.

The new documents were filed in a case brought almost four years ago by Cambridge Place Investment Management, an asset-management company based in Boston that sought $1.8 billion in damages on roughly 200 mortgage securities it had bought from 16 banks in the years before the crisis. Cambridge Place, which has settled with 14 of those banks, is represented by the law firm Bernstein Litowitz Berger & Grossmann.