Prison officials say 50-year-old Noah Rutherford was attacked in November by his cellmate, 47-year-old Steven Law.
Rutherford died Sunday evening from his injuries. He was serving a 30-year sentence for multiple counts of lewd acts with a minor under 14 with force, violence or fear committed in Los Angeles County..
Law is serving a life sentence for a robbery committed in Tulare County.
An investigation is underway to determine what led up to the attack.