Silverstein was serving three consecutive life terms in connection with the Oct. 22, 1983, slaying of two fellow prisoners and a guard, The New York Times reported. The prison guard, Merle Clutts, was fatally stabbed at the maximum security federal prison in Marion, Illinois, the Post reported.
Silverstein was originally sent to prison in 1975, convicted for armed robbery, the Times reported.
Because there was no federal death penalty at the time, the Bureau of Prisons put Silverstein into indefinite solitary confinement, according to the Post.
Through the years, Silverstein was incarcerated in Marion; Leavenworth, Kansas; Atlanta; and in Colorado, the Post reported.