Thomas Silverstein's murder of a guard at the federal penitentiary in Marion, Illinois led to the creation of ADX Florence. He currently holds the U.S. record for solitary confinement by a federal prisoner, having been held in solitary since 1983. He is one of the co-leaders of this gang which accounts for the largest number of prison murders in the federal system. Name this gang that was an important plot point in the film American History X.
Aryan Brotherhood