A lawyer for Bernard L. Madoff, awaiting sentencing for swindling billions of investors' dollars in one of history's biggest frauds, has asked a federal judge to sentence the disgraced financier to as few as 12 and no more than 20 years in prison, citing cooperation with federal officials.

Madoff attorney Ira Sorkin said in court papers made public yesterday that his client "will speak to the shame he has felt and to the pain he has caused" when U.S. District Judge Denny Chin sentences him.

"We seek neither mercy nor sympathy," Sorkin wrote. But he urged Chin to "set aside the emotion and hysteria attendant to this case" as he determines the sentence.

Madoff, 71, is to be sentenced on Monday. He pleaded guilty in March to 11 felony counts, including securities fraud and perjury. He admitted operating a massive Ponzi scheme in which he paid off old investors with money from new clients.

Customers who invested through his securities firm were told in the weeks before the fraud came to light in December that their accounts were worth as much as $65 billion. Their actual losses, however, were about one-quarter of that, prosecutors say.

Madoff faces up to 150 years in prison under federal sentencing guidelines. He has been in a federal jail in lower Manhattan since March, awaiting sentencing.

In the court filing, Sorkin said a 12-year sentence would be appropriate because Madoff's life expectancy was 13 years. As an alternative, he said, a term of 15 to 20 years would achieve the goals of sentencing "without disproportionately punishing Mr. Madoff."

Other white-collar offenders facing life in prison received an average sentence of 184 months, or about 15 years, Sorkin said, citing a study conducted by Herbert Hoelter, a sentencing consultant hired by Madoff.

"If we he was hung by his toes for 12 years then maybe that sentence would be acceptable," said Candace Newlove of Nederland, Colo. She said in a letter to the court that her family was financially ruined by Madoff.

Newlove, who is selling her home, said she hoped the judge kept in mind that Madoff "had a huge impact not only on our family but world economics and trust around the world."

Prosecutors have identified 1,341 Bernard L. Madoff Investment Securities L.L.C. account holders who collectively suffered losses of more than $13 billion, they said in a June 19 court filing.

The government is expected to file its own pre-sentencing brief this week.

Jesse Cohen, a Summit, N.J., man who called Madoff a "thief and a monster" in a letter to the court released yesterday, said he trusted that the judge would be fair at sentencing.

In the letter to Chin, Sorkin said Madoff sought something less than a "de facto" life sentence. He cited "Mr. Madoff's voluntary surrender, full acceptance of responsibility, meaningful cooperation efforts" and the nonviolent nature of his crime.

"We believe that the unified tone of the victim statements suggests a desire for a type of mob vengeance that, if countenanced here, would negate and render meaningless the role of the court," Sorkin said.

The Associated Press contributed to this article.