Hernandez's latest troubles behind bars come just a few months after he was involved in a third prison fight at the Souza Baranowski Correctional Center in August. Hernandez reportedly served as a lookout in a gang-related prison fight in May, and also reportedly attacked an inmate last year while awaiting his trial.
Upon discovery of the knife, Hernandez was placed in a segregated unit, according to WHDH Channel 7 news.
Hernandez, 25, was convicted of the first-degree murder of semi-pro football player Odin Lloyd, who was dating his fiancee's sister. He was sentenced to life in prison for the June 2013 killing without the possibility of parole and is appealing the sentence. He has also been charged with two counts of first-degree murder for shooting two men in July 2012 after an altercation at a Boston night club and is expected to go to trial in January.