Bernie Madoff has returned to prison after being hospitalized in December for a heart attack.
The 75-year-old inmate and convicted Ponzi scheme mastermind was hospitalized at Duke University Medical Center last month before returning to the medium security federal prison in nearby Butner, N.C., CNBC reports. An official at the prison complex told TIME that Madoff is back in prison but declined to comment on his medical condition.
Madoff was convicted of running the largest investment fraud in U.S. history, bilking his 4,800 clients out of billions of dollars over 20 years. He has stage four kidney disease and is not receiving dialysis.