Twenty-five police have been given long sentences for their part in the 1992 massacre in Sao Paulo's Carandiru jail that left 111 prisoners dead.
Each officer received 624 years for the death of 52 inmates, but in Brazil no-one serves more than 30 years in jail.
The verdicts come in the second of four stages of the trial involving different floors of the prison. Twenty-three officers were convicted in April.
The police are expected to stay free pending an appeal.
The defence can only challenge the verdicts after the end of the whole trial, expected in January 2014.
Under Brazilian law there are no life sentences, and no convicted person can serve longer than 30 years in jail.
The officers, nine of whom are still on active duty, will also lose their jobs, O Globo newspaper reported.
The riot began on 2 October 1992 after an argument between two inmates quickly spread, with rival gangs facing off in what was at the time one of South America's largest prisons, housing 10,000 inmates.
Inmates said riot police brutally repressed the riot.
The officers' lawyer, Ieda Ribeiro de Souza, argued they were only doing their duty and acted in self-defence, as many of the inmates were armed.
While prison riots are not uncommon in Brazil, the number of those killed at Carandiru and the slow pace of the Brazilian justice system in bringing the accused to trial shocked the public.
Carandiru was closed in 2002, shortly after inmates co-ordinated simultaneous uprisings in 27 jails across Sao Paulo state during which thousands of visitors were held hostage.
In 2001, Col Ubiratan Guimaraes, who led the police operation to regain control in Carandiru, was convicted of using excessive force. But he was acquitted on appeal in 2006.