Aaron Hernandez was found with a shank-like weapon in his cell and has been moved to a segregated unit at Souza Baranowski Correctional Center in Massachusetts, according to multiple reports.
Guards found a prison-made knife during a shakedown of Hernandez's cell Thursday, WHDH.com reported, citing sources. He was immediately taken out of general population, according to the website.
The Massachusetts Department of Correction, which runs the correctional center, would not comment, according to reports.
Hernandez, a former New England Patriots tight end, is serving a life sentence in the 2013 killing of Odin Lloyd, who was dating the sister of Hernandez's fiancée.
This isn't his first reported trouble.
In May, CNN reported that Hernandez agreed to be on the lookout for one inmate who went into another prisoner's cell at the correctional center. The two inmates fought, with a source telling CNN the altercation was believed to be gang-related. All three inmates were disciplined, and Hernandez was placed in a special management section.
And in 2014, Hernandez was indicted in an alleged jail assault in which he and an inmate being transported from an infirmary at the Bristol County House of Correction in Dartmouth, Massachusetts, allegedly exchanged words. Hernandez allegedly punched the inmate and knocked him to the ground. Neither was injured.
Hernandez also is set to go to trial for a 2012 double murder case in Boston. That is scheduled to begin in early January.