Altogether 56 prisoners were killed in the riot. It was Brazil's worst prison massacre since Carandiru in Sao Paulo in 1992, when the military police killed 111 prisoners.
The riot was part of a wider wave of prison violence: more than 130 Brazilian prisoners have been killed since the beginning of this year - many decapitated, dismembered or burned - in a series of uprisings that have shocked a country long accustomed to this kind of violence. In 2016, 379 inmates were killed.
Experts say that the prison killings reflect decades of failed policy; the prison population has soared beyond the control of a chronically underfunded system, enabling gangs to step in and take the place of the state.
The upsurge in violence is also attributed to growing tensions between gangs fighting for control of the cocaine trade.
Following the prison violence, hopes have been spurred for prison reform and a rethink on drug decriminalisation - outcomes considered essential by some experts to prevent further bloodshed.
But any kind of drug reform is likely to encounter resistance within Brazil's conservative Congress, home to a powerful Evangelical Christian caucus, where there are currently 14 proposed projects to make drug laws even tougher.
For the Igapare Institute's Szabo de Carvalho, however, any discussion of drug decriminalisation is a step in the right direction, even if initially voted down in Congress.
"We had a horror show in January, if we forget what happened; we are going to go back to that in a few months," she said.