Although there are many differences between the two , Sona is based on , or at least inspired by , the notorious Carandiru Penitentiary , a prison which was operational from 1956 to 2002 in São Paulo City , Brazil but was most well known for a 1992 massacre . As explained in the first episode of Season 3 , it seems that anyone who gets put into Sona is there for life . Due to a prison riot the year before Season 3 takes place , Sona is no longer run by guards from within . Instead , guards only patrol from outside on the boundaries , leaving the prisoners to fend for themselves inside the walls . As stated by Lechero , it is only rules that will stop the inmates from becoming savages , and as such , Lechero runs Sona on the inside , with his rules in place
1992 massacre
Carandiru massacre
Penitenciaría Federal de Sona