Gang war in Brazil's Pedrinhas jail kills 59 in 2013
Fifty-nine inmates have been killed in a single northern Brazilian prison this year, according to a judicial report.
Video taken inside the Pedrinhas prison in Sao Luis also shows the torture of one inmate at the hands of others - and cases of beheadings.
The district judge who wrote the report said the video was the "most barbarous scene" he had ever witnessed.
Brazil has the world's fourth largest prison population with half a million inmates occupying spaces for 300,000.
The report contains details of sexual relations between prisoners taking place in open spaces, horrific scenes of torture and at least 59 deaths, including the beheading of three prisoners, in the last year.
Across the country, many poorly resourced jails are, in effect, run by powerful crime gangs and the government is looking again at a greater role for privately run prisons, says the BBC's Wyre Davies in Rio de Janeiro.
A judicial report into a prison in the northern Brazilian state of Maranhao has exposed some shocking conditions of torture, sexual abuse and murder.
The report, now handed over to Brazil's Supreme Court, describes a desperately overcrowded facility where the prison authorities have lost control and where punishment or retribution is handed-out on a daily basis by gangs. One video, obtained by a newspaper shows the slow torture of one inmate until he dies.
Pedrinhas, in the state of Maranhao, is notorious for its gang warfare; fighting between inmates in October left 13 dead and 30 injured.
Brazil's Minister of Justice, Jose Eduardo Cardozo, said last year that Brazil had "a medieval prison system, which not only violates human rights [but] does not allow for the most important element of a penal sanction, which is social reintegration".
Officials say that despite building new prisons they have not been able to keep pace with the increasing number of detainees, making it hard for them to improve conditions within the jails.