RIO DE JANEIRO • Some of the inmates were beheaded. Others had their hearts torn from their bodies. Gang leaders used the blood of their victims to write a nightmarish message of retribution: "Blood is paid for with blood."
The harrowing scenes on Friday from the latest prison riot in Brazil, in which 33 inmates were killed in the northern state of Roraima in the Amazon River Basin, pushed the death toll to 95 in six days of mayhem in penitentiaries around the country.
The bloodshed has shocked the country and is emerging as the most pressing crisis facing President Michel Temer, whose beleaguered government was already grappling with graft scandals, a weak economy and simmering anger over austerity measures.
"The bloodshed is revealing a war between drug gangs, a failed prison system and a weak government," said Mr Rafael Alcadipani, a scholar who specialises in public security policies at the Getulio Vargas Foundation, a Brazilian think-tank. "And now the horror is spreading."
Prison violence that has spilled out into neighbouring communities has been a perennial problem in Brazil. In 2006, street fighting between the police and First Capital Command, a prison-based gang, left almost 200 people dead in Sao Paulo, causing chaos in the city.
The killings in Roraima came just days after 56 men were killed in a massacre at a prison in the city of Manaus. In two other riots at prisons this week in the states of Amazonas and Paraiba, six men were killed.
The violence at the Monte Cristo Agricultural Penitentiary in Boa Vista, the capital of Roraima, adds to fears about an intensifying war between drug gangs for control of the cocaine trade in the Amazon region in Brazil.
The latest episode is thought to involve fighting between First Capital Command, commonly known by its Portuguese initials, PCC, which has roots in the prisons of Sao Paulo in south-east Brazil, and supporters of Red Command, a drug-trafficking organisation that has long held sway in Rio de Janeiro.
The authorities, however, tried to play down the possibility that warring gangs were to blame. The gangs, which operate inside prisons as well as on the streets of many Brazilian cities, are battling for supremacy over the trade in cocaine smuggled into Brazil across the porous Amazonian frontier from countries such as Bolivia, Colombia and Peru.
President Temer has been chided for what some have called a tone-deaf response to the crisis. He said nothing for two days about the killings in Manaus before calling them a "dreadful accident" and seeking to deflect blame from public agencies because a private contractor runs the prison there.
Brazil has a prison population exceeding 500,000, with about 40 per cent of detainees awaiting trial.
Drug gangs that originated in prisons are expanding their sway and battling one another for territorial control of the trade.
"This war between the criminal factions is worsening," said Mr Antonio Claudio Mariz de Oliveira, a former security official in Sao Paulo. "The problem is largely a result of the lack of attention towards the prison system, both by the government and the public. People only react when there's an episode like this," he said.