(CNN) -- Argentina's last dictator and five military leaders who helped rule the country more than 25 years ago went on trial Monday on human rights charges.
Former Gen. Reynaldo Benito Bignone, who ruled Argentina from June 1982 until the nation's return to democracy in December 1983, is accused of torturing 56 people and depriving them of their liberty, as well as committing illegal searches, federal court papers say.
Justice Minister Julio Alak and human rights leaders attended Monday's hearing in Argentina's capital, Buenos Aires, the government-run Telam news agency said.
"This is one of the most-anticipated trials by the community and by human rights organizations because of the magnitude of the crimes that were committed there," Alak is quoted as saying.
Also facing the same charges are former intelligence chief Fernando Ezequiel Verplaetsen and ex-military officials Santiago Omar Riveros, Eugenio Guanabens Perello, Carlos Alberto Tepedino and German A. Montenegro.
Another defendant, Eduardo Alfredo Esposito, was deemed at the last minute "not have sufficient mental faculties" to stand trial, the Telam news outlet said. The court recommended that Esposito be re-evaluated in six months.
The alleged crimes occurred at the secret Campo de Mayo torture center in Buenos Aires, court papers say. Campo de Mayo was the main torture center during the 1976-83 right-wing dictatorship. Few who were taken there walked out alive.
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 eight-year "Dirty War."
Verplaetsen, the former intelligence chief, was excused from attending Monday's opening proceedings because he had diarrhea, Telam said.
More than 100 family members attended Monday's hearing, some of them holding up large photos of victims as the defendants walked in.
About 130 witnesses, many of them survivors from Campo de Mayo, will testify in a trial expected to last until March 2010, the court said.
The trial will be held Tuesday, Wednesday and Thursday for a maximum of five hours a day, in order to preserve the health of the elderly defendants.
Bignone, 81, has been under house arrest. He faces two other trials: in the abduction and disappearance of doctors and nurses at the Hospital Posada and of two soldiers when he was head of the Military College.
Other suspects from the nation's Dirty War also face trial in the coming weeks, with hearings scheduled to start November 17 and 24 and December 15.
Trials for other suspects have not been set. Argentina recently announced the arrests of two men accused of piloting aircraft from which drugged and blindfolded prisoners were hurled to their deaths in the Atlantic Ocean or the Rio Plata. Authorities say the two pilots participated in "death flights" in which more than 1,000 prisoners were thrown out of aircraft.
One of the suspects was arrested in Spain and would have to be extradited to Argentina for trial.