This request was made in a letter filed in Manhattan federal court on Friday.
According to the letter, Bankman-Fried reached out to the current General Counsel of FTX US, Ryne Miller, who may be a witness at trial via Signal on January 15th. Prosecutors claim that Bankman-Fried's overtures to Miller constitute a possible attempt at witness tampering.
In addition, the government cites a need to "prevent obstruction of justice" by restricting Bankman-Fried's access to Signal and other encrypted messaging platforms. Prosecutors claim that Bankman-Fried directed Alameda and FTX through Slack and Signal and ordered his employees to set communications to "autodelete after 30 days or less."
The DOJ also cites previously undisclosed testimony from ex-Alameda CEO Caroline Ellison, who has pleaded guilty to multiple fraud charges and is cooperating with the U.S. Attorney's efforts to build a case against Bankman-Fried.
Bankman-Fried pleaded not guilty to eight charges concerning the collapse of his multibillion-dollar crypto empire, FTX. He is due in federal court in October after being released on $250 million bond.