It may not technically be theft, but surely there’s an assortment of crimes committed by doing what he did, including but not limited to fraud, conspiracy, and interference with an investigation.
- removal of property to prevent seizure (18 USC 2232)
- money laundering (18 USC 1956)
- obstruction of a criminal proceeding (18 USC 1512)
- lying to federal law enforcement agents
Also, the BTC were subject to forfeiture pending the resolution of the indictment against his brother.