In effect, they argued, prosecutors have been “outsourcing” the legal requirement to provide potentially helpful material to the defense team, shifting that responsibility to a “private party” with no obligation to Mr. Bankman-Fried.

Representatives for FTX, Sullivan & Cromwell and the U.S. Attorney’s Office in Manhattan did not immediately respond to requests for comment.

Federal prosecutors have charged Mr. Bankman-Fried with orchestrating a vast fraud that misappropriated billions of dollars in customer money from FTX. The authorities have also charged him with money laundering, bribing the Chinese government and overseeing an illegal campaign finance scheme that showered tens of millions of dollars on Democratic and Republican candidates.

Mr. Bankman-Fried, 31, has pleaded not guilty to those charges. His lawyers at the New York firm Cohen & Gresser have said they are prepared to go to trial in federal court in Manhattan as soon as October.

Mr. Bankman-Fried was released on bail in December but confined to his parents’ home in Palo Alto, Calif. He faces an uphill legal battle. Three of his top colleagues have pleaded guilty and are cooperating with prosecutors. If convicted, he could spend decades in a federal prison.