Mouths open, eyes closed, faces spattered with blood, two freshly decapitated heads lie on a filthy floor. A pushcart full of dismembered limbs stands in front of a wall of iron bars as men yell in the background. These are just two of many brutal scenes captured in shaky cell phone videos that spread across Brazil in January 2017.

The Northern Family criminal syndicate had staged a rebellion at the overcrowded Anísio Jobim prison complex in the Amazonian city of Manaus, home to over 1,200 prisoners, more than double its maximum capacity. Within hours, they had executed fifty-six alleged members of their São Paulo–based rival, the First Command of the Capital, or PCC, the most powerful syndicate in Brazil.

Days later, 450 miles to the north, the PCC responded at another penitentiary in the state of Roraima with thirty decapitations. Videos of human hearts being removed from bodies made the rounds on messaging apps. “Here is the answer for you — you killed our brothers in Manaus, and now you’re going to pay for it.” It was a particularly gruesome episode in a cycle of violence that the Brazilian government appears powerless — or unwilling — to stop.