Tommy Silverstein - one of the leaders of the Aryan Brotherhood prison gang in the United States - killed three men behind bars in the space of two years, one of whom was a prison guard. The federal Bureau of Prisons reacted by locking him up in solitary for decades. 20 years ago I wrote to Silverstein in a supermax prison. Find out what happened next in this episode, in which I tell the full story of "Terrible Tommy" Silverstein and the Aryan Brotherhood.