Jason Reid pleaded guilty in February to the Thanksgiving Day attack.
He is expected to be sentenced to eight years in prison for the attack, 1 1/3 to 3 for another assault in Rikers, and 10 years for home invasion case.
Sentencing was postponed last month after Reid claimed to be sick.
Surveillance video showed Reid jump on Captain Awais Ghauri inside the Otis Bantum Correctional Center, punch him in the face, and then knock him to the floor.
Two other inmates then joined in on the beating.
Authorities say Reid called a meeting to plan the attack.
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