Jeffrey Epstein, the disgraced millionaire who was facing federal sex trafficking charges, has died by suicide in his Lower Manhattan jail cell, three law enforcement officials told ABC News Saturday morning. The exact timing and circumstances were not immediately clear. Epstein, 66, was set to stand trial next year for allegedly sexually abusing dozens of minor girls in New York and Florida. (MORE: The rise and fall of Jeffrey Epstein: A timeline of the financier's legal troubles) His death came less than three weeks after he was found unresponsive in his cell at Metropolitan Correctional Center in Lower Manhattan, with marks on his neck that appeared to be self-inflicted, sources told ABC News. He had been on suicide watch since the July 23 incident. Epstein, 66, pleaded not guilty to the charges. He faced up to 45 years in prison if convicted. This is a developing story. Please check back for updates.