(Reuters) - Former cryptocurrency executive Caroline Ellison urged a federal judge not to send her to prison after she pleaded guilty over her role in the theft of $8 billion from customers of Sam Bankman-Fried's bankrupt FTX exchange.

In a court filing just before midnight on Tuesday, Ellison's lawyers told U.S. District Judge Lewis Kaplan in Manhattan that she deserves leniency for helping prosecutors build a successful criminal case against Bankman-Fried, her onetime boyfriend.

"From her first meeting with prosecutors, Caroline unflinchingly acknowledged her own wrongdoing," her lawyer Anjan Sahni wrote. "She time and again proved herself an enormously credible and important cooperating witness."

Ellison, 29, is scheduled to be sentenced on Sept. 24.

Bankman-Fried, 32, is serving a 25-year prison sentence after his conviction last year in what prosecutors described as one of the biggest financial frauds in U.S. history. He is appealing the verdict and sentence.

A spokesman for Bankman-Fried declined to comment on Wednesday. A representative of U.S. Attorney Damian Williams in Manhattan, whose office prosecuted Bankman-Fried and Ellison, did not immediately respond to a request for comment.

Ellison pleaded guilty to fraud and conspiracy charges in December 2022, just over a month after FTX's dramatic collapse.

The meltdown jolted financial markets and shattered Bankman-Fried's reputation as a charitable, politically involved wunderkind entrepreneur.

At Bankman-Fried's trial, Ellison and two other former colleagues testified that the former billionaire directed them to use FTX customer funds to plug losses at his cryptocurrency-focused hedge fund Alameda Research, where Ellison was chief executive.

In emotional testimony, Ellison also gave jurors an intimate window into Bankman-Fried's values and character.

She said the self-described "utilitarian" thought doing what he considered the greatest amount of good for the greatest number of people was more important than following rules such as "don't lie" or "don't steal."

Former FTX executives Nishad Singh and Gary Wang, who also pleaded guilty to fraud and testified against Bankman-Fried, face sentencing hearings on Oct. 30 and Nov. 20, respectively.

Ryan Salame, a former FTX executive who did not cooperate with prosecutors, was sentenced to 7-1/2 years in prison in May after pleading guilty to making unlawful campaign donations to causes supported by Bankman-Fried.