Buenos Aires (CNN) -- An Argentine court convicted and sentenced eight former army officers to life in prison for human rights violations during the country's so-called Dirty War. One officer was acquitted.

The case involved some of the most infamous abuses of the 1976-1983 dictatorship. It is known as the "Margarita Belen" case, named after the town where the abuses took place. The ruling came down Monday.

The officers were convicted of aggravated murder of 11 victims, and with their illegal detention and forced disappearances.

Up to 30,000 students, labor leaders, intellectuals and leftists who ran afoul of the dictatorship because of their political views disappeared or were held in secret jails and torture centers during the nation's eight-year Dirty War.

The convicted officers were Athos Gustavo Renes, Horacio Losito, Aldo Martínez Segon, Jorge Daniel Carnero Sabol, Ricardo Guillermo Reyes, German Emilio Riquelme, Ernesto Jorge Simoni and Luis Alberto Patetta.

Alfredo Luis Chas was found not guilty.

The massacre of Margarita Belen, as it is known, happened on December 13, 1976. According to historians, a group of prisoners, mostly belonging to the urban guerrilla group known as the Montoneros, were gathered together and executed while being transported to another prison. According to those accounts, authorities claimed falsely that their convoy came under attack.