On this day, Oct. 22, in 1983, two correctional officers were killed by inmates at the United States Penitentiary in Marion, Illinois. The incident inspired the “Supermax” model of prisons.

Opened in 1963 to replace Alcatraz, Marion became the United States’ highest security prison by 1978. In separate incidents, two prison guards, Merle E. Clutts and Robert L. Hoffman, were killed by members of the Aryan Brotherhood.