The federal judge who oversaw the trial of five associates of imprisoned swindler Bernard Madoff on Thursday refused to overturn their convictions for helping their former boss run one of the world's biggest Ponzi schemes.

U.S. District Judge Laura Taylor Swain found sufficient evidence for jurors on March 24 to have convicted back-office director Daniel Bonventre, portfolio managers Annette Bongiorno and Joann Crupi and computer programmers Jerome O'Hara and George Perez after the five-month trial.

Swain also said the defendants were not entitled to a new trial, rejecting arguments that prosecutors had made prejudicial remarks during their opening and closing statements, including referring to their defenses as "ridiculous" and "absurd."

"Although the court had expected the government to take a higher and less rhetorical road," Swain wrote, "the government's summation - when considered in the context of the meticulous presentation of all of the evidence, arguments in the trial as a whole and the curative instructions - did not so taint the trial so as to make it fundamentally unfair."

Judges give jurors curative instructions to eliminate the risk of prejudice from tainted statements or evidence.

"This is a thorough and comprehensive decision by the judge," Bongiorno's lawyer Roland Riopelle said in an interview. "She is doing her job to the best of her ability, and I cannot find fault with that even if I disagree."

O'Hara's lawyer Gordon Mehler said he is disappointed with the decision. Perez's lawyer Larry Krantz declined to comment. Lawyers for Bonventre and Crupi did not immediately respond to requests for comment. Jim Margolin, a spokesman for U.S. Attorney Preet Bharara in New York, declined to comment.

The defendants were convicted on all counts they faced, including securities fraud, conspiracy to defraud clients, falsifying records and violating tax laws at Bernard L. Madoff Investment Securities LLC. Not all defendants faced each count.

Sentencings are scheduled for mid-September.

Prosecutors have requested "very severe" punishments, including prison terms of more than 20 years for Bonventre and Bongiorno, more than 14 years for Crupi and more than eight years for O'Hara and Perez.

Madoff, 76, is serving a 150-year prison term. The trustee liquidating his firm has estimated that the fraud caused customers to lose about $17.5 billion of principal.

The case is U.S. v. O'Hara et al, U.S. District Court, Southern District of New York, No. 10-cr-00228.