The judge who issued the report called the situation at the Pedrinhas prison in Sao Luis "the most barbarous scene" he had ever witnessed.
The report was submitted to Brazil's supreme court for further action.
The BBC Saturday described Pedrinhas as hopelessly outdated and overcrowded, with various gangs virtually running the facility. The gangs target inmates for punishment and retaliation on nearly a daily basis with little interference from undermanned guards.
The judicial report, which included videos, tallied incidents in which inmates were tortured and even beheaded in the past year. A single riot in October accounted for 13 deaths and 30 injuries.
The Brazilian government has conceded that while it is building new prisons, it is being overwhelmed by its spiraling inmate population, the fourth-largest in the world, the BBC said.