Nishad Singh, who was a top adviser to the disgraced cryptocurrency mogul Sam Bankman-Fried, avoided prison time for his role in the collapse of the FTX crypto exchange, after a federal judge on Wednesday lauded his cooperation with U.S. prosecutors.

Mr. Singh, 29, was sentenced to three years of supervised release at a hearing in Federal District Court in Manhattan, an unexpected reprieve after Mr. Bankman-Fried and two other FTX executives received long sentences. Judge Lewis A. Kaplan, who has presided over the cases, said that Mr. Singh provided crucial assistance to the government and that he had played a “much more limited” role in the scheme than his colleagues had.

“I’m not foolish enough to think there was no self interest involved,” Judge Kaplan said of Mr. Singh’s cooperation. “But you did the right thing.”

Not long after FTX failed in November 2022, Mr. Singh pleaded guilty to participating in the fraud that drained $8 billion from customers’ accounts. He also admitted to breaking campaign finance rules by serving as a so-called straw donor — making political donations in his name with money that actually came from the company. Lawyers for Mr. Singh had requested that he serve no prison time, while prosecutors also called for leniency.

Mr. Singh is one of several executives in Mr. Bankman-Fried’s former business empire who were charged with fraud. In March, Mr. Bankman-Fried, 32, was sentenced to 25 years in prison after his conviction at trial last year on seven counts of fraud and conspiracy.

The other executives who have been sentenced all pleaded guilty to various financial crimes. Caroline Ellison, another top lieutenant to Mr. Bankman-Fried, was sentenced to two years in prison at a hearing in federal court last month. Ryan Salame, an FTX executive, received a seven-and-a-half-year sentence in May for campaign finance violations. And Gary Wang, a fifth company leader, is scheduled to be sentenced on Nov. 20.