Ilya Lichtenstein, who pleaded guilty to the 2016 theft of 120,000 Bitcoin from Bitfinex, refutes claims of third-party involvement in the hack.
Lichtenstein admitted to planning and executing the Bitfinex heist alone and denied any involvement of his father or external parties.
The stolen Bitcoin, valued at $72 million at the time, is now estimated to exceed $12.6 billion in current market value.
Lichtenstein has been cooperating with authorities to return the stolen funds and plans to work in the cybersecurity industry upon release from prison.