Sam Bankman-Fried's lawyers agreed to pay for an expert to explain VPNs and disappearing messages to the judge in his case

• Sam Bankman-Fried has been banned from using VPNs and auto-deleting messaging apps while on bail.
• Judge Lewis Kaplan then warned about sending the FTX cofounder back to jail over his use of electronics.

Lawyers for the FTX cofounder Sam Bankman-Fried wrote to the judge presiding over his criminal case on Tuesday, agreeing to pay for an expert to help explain virtual private networks (VPNs) and disappearing messages.

The letter, signed by Bankman-Fried's attorney Christian Everdell and viewed by Insider, said lawyers agreed to the appointment of "an independent technical expert, paid for by the defense, to advise the Court on technical issues concerning Mr. Bankman-Fried's bail conditions."

US District Judge Lewis Kaplan has warned Bankman-Fried several times over his use of technology while under house arrest at his parents' home in Palo Alto, California.

In late January, prosecutors alleged that Bankman-Fried may have engaged in witness tampering after he reached out to FTX employees via the encrypted messaging app Signal. Kaplan then banned him from using any apps which encrypt or auto-delete messages. He added concerns that Bankman-Fried could still figure out a way to conceal communications, saying: "I've read all the spy novels."

On February 13, prosecutors raised concerns about Bankman-Fried's use of a VPN, which masks a user's web-browsing activity and location. His lawyers said that Bankman-Fried was only watching the Super Bowl and other NFL games through an international subscription he purchased in the Bahamas, but Kaplan still ordered him to stop using a VPN.

In a February 15 letter to the court, Assistant US Attorney Nicolas Roos described Bankman-Fried as "a technologically sophisticated person with both the ability and the inclination to seek workarounds of more narrowly drawn bail conditions."

Last week, CNN reported the judge as saying Bankman-Fried could "conceivably" be sent back to jail as a result of his use of electronics while on bail. Per the Financial Times, Kaplan said: "Why am I being asked to turn him loose in this garden of electronic devices?"

The 78-year-old judge then proposed that the defense pay for an expert to advise him on VPNs and other technical matters related to Bankman-Fried's bail conditions, per CNN. His attorneys now say they expect to put forward candidates by the end of the week.

In January, Bankman-Fried pleaded not guilty to eight criminal charges including wire fraud and money laundering. Bankruptcy lawyers said he had access to $65 billion of customer funds through a "secret" backdoor, and the SEC alleged he used his hedge fund as a "personal piggy bank" for luxury purchases.

A spokesperson for Bankman-Fried did not immediately respond to Insider's request for comment, sent outside US working hours.