Such a sentence, the maximum recommended under federal sentencing guidelines, would be 80 years longer than Bernard Madoff got in 2009 for his Ponzi scheme, and according to prosecutors reflects Stanford's place as "among the greediest, most selfish, and utterly remorseless criminals."

Stanford's lawyers are seeking a prison term of 31 to 44 months for their client, which could result in his immediate release because he has already been in custody for three years, according to the government.

Once considered a billionaire but later declared indigent, Stanford was convicted on March 6 by a federal jury in Houston on fraud, conspiracy and obstruction charges.

Prosecutors said he ran a two-decade scheme centered on the sale of bogus certificates of deposit from his Antigua-based Stanford International Bank Ltd.

"Robert Allen Stanford is a ruthless predator responsible for one of the most egregious frauds in history," prosecutors said in a filing in U.S. District Court in Houston. "The sheer magnitude of the money stolen, the duration of the crime, and the extent to which Stanford lived a life steeped in deceit are almost unrivaled."

Saying that Stanford's request reflected "an audacity that only further illustrates his depravity," prosecutors countered that "the nature and circumstances of Stanford's fraud, his own role and personal history, and the need for forceful deterrence calls for the most severe punishment permitted by law."

Robert Scardino, a lawyer for Stanford, in a phone interview said: "We feel like our recommendations are every bit as appropriate as I'm sure they think theirs are."

U.S. District Judge David Hittner, who presided over Stanford's six-week trial, is scheduled to sentence Stanford on June 14.

In addition to convicting Stanford on 13 criminal counts, the jury also found that federal authorities should try to seize $330 million of frozen funds that Stanford stashed in 29 foreign bank accounts.

Stanford also faces civil charges by the U.S. Securities and Exchange Commission.

The case is U.S. v. Stanford, U.S. District Court, Southern District of Texas, No. 09-cr-00342.