Sam Bankman-Fried deleted a number of messages — including a Slack message from FTX's own general counsel that warned the crypto exchange needed to shut down — prosecutors said. Prosecutors alleged that Bankman-Fried had a practice of talking to employees on Signal using auto-deleting messages, "in part to prevent the preservation of evidence that could be used against him," according to the indictment. US, in a Signal chat that included Bankman-Fried and several close associates, demanded: 'I need to know the fucking truth about FTX US right now,'" prosecutors wrote in the new filing