Bristol County Sheriff Thomas Hodgson said jail staff are interviewing witnesses and reviewing surveillance video to figure out exactly what happened.
The state plans to appeal the ruling in the case of Michelle Kosilek, who was born as a man but lives as a woman in an all-male prison.
A group of 50 Massachusetts legislators has asked the state Department of Correction to appeal a ruling from a federal court judge who ordered prison officials to provide sex-reassignment surgery to a transgender inmate.
The victim, Richard Silva, 64, formerly of Lowell, was serving a 9 to 10 year sentence for assaulting a child.
A grand jury has indicted a former Essex County Correctional Facility employee for having sex with an inmate.
Officials say a Boston man is the suspect in the beating of an inmate at the county jail in Dover, N.H.