Former Argentinian military ruler Jorge Videla has gone on trial for the killing of political prisoners after he seized power in 1976.
The 84-year-old, who is already serving a life sentence for abuses committed during military rule, is one of more than 20 defendants.
A presidential pardon given to him in 1990 was recently overturned by the supreme court.
Up to 30,000 people were tortured and murdered between 1976 and 1983.
As the head of the military junta until 1981, Videla is considered to have been the main architect of what became known as the "Dirty War".
The case now being heard relates to the killing of a group of left-wing activists who were taken from their jail cells in the city of Cordoba and shot dead shortly after the military took power.
The army said at the time that they were killed while trying to escape.
Videla, who has prostate cancer, was sentenced to life in prison for torture, murder and other crimes in 1985 when many of Argentina's military leaders were tried for human rights abuses.
The BBC reports that since he is already serving a life sentence, any new conviction will not mean more years of prison.
But the prosecution hopes the trial in Cordoba will bring some relief to the families of the dead.
During his five-year administration, Videla organised the 1978 World Cup in Argentina.
Argentina's victory was used to try to clean the international reputation of the military government at a time when reports of massive human rights violations had been seeping out, the BBC reports.
Videla also faces charges in Italy, Spain France and Germany for the murder of some of their citizens in Argentina.