The former Argentinian dictator Jorge Rafaél Videla was a prominent member of the group of uniformed tyrants who in the 1970s seized power in Latin America and turned "disappear" into a transitive verb. If he never achieved the worldwide notoriety of his contemporary Augusto Pinochet, in Chile, it was not for want of trying. He has died aged 87 while in prison.

"As many people as is necessary will die in Argentina," Videla told the region's army commanders, gathered in Montevideo, Uruguay, in 1975, "to protect the hemisphere from the international communist conspiracy." He was true to his word. Months later, on 24 March 1976, the armed forces overthrew the inept and chaotic government of María Estela Martínez ("Isabelita"), the widow of Juan Domingo Perón.

They installed a ferocious military regime. During the next six years, it murdered up to 30,000 people in the name of "national reorganisation" and western, Christian civilisation.

For Videla, who as army commander was chosen to head the junta, the decision to "disappear" the victims was purely pragmatic. "Argentinian society would not have tolerated firing squads," he told a journalist many years later. "Yesterday two in Buenos Aires, today six in Córdoba, tomorrow four in Rosario … There was no other way. We all agreed on that."

Videla was a methodical, introverted man from a provincial military family. Born in Mercedes, to the west of the capital, he was brought up beside the Buenos Aires barracks where his father, a colonel, was serving. The family were strict Catholics. When sentenced to house arrest in later life, his greatest regret, he said, was that he could not attend mass. Other than that, his social life was almost nonexistent.

Like Pinochet's, his military career was a largely routine affair – a steady climb up the ranks until he reached the top. In 1975, after the death of Perón, Isabelita appointed him army commander, under pressure from the military hierarchy. It was a decision she would live to regret. Videla had been a convinced anti-Perónist for at least 20 years, and he proceeded to purge the caudillo's followers from positions of command.

The country was in the grip of political violence. Leftist guerrillas battled the government, while rightwing death squads cruised the streets, murdering with impunity. Many ordinary citizens sighed with relief when the military stepped in, and looked the other way as it installed an unprecedented system of repression.

Not just guerrillas, but trade unionists, journalists and dissidents of all kinds were kidnapped, tortured and killed. Thousands were thrown from planes over the river Plate, in a usually successful bid to "disappear" their bodies for ever.

The brutal repression of all opposition facilitated an economic policy, run by José Martínez de Hoz, which dismantled Perón's pro-labour laws, opened up the economy to foreign capital and vastly increased the country's external debt. Many years later, it was revealed that the coup had been planned by business interests allied with hardliners in the armed forces. Videla presided over this butchery until his retirement in 1981, although for the last year – having reached the end of his military career – he was formally subordinate to the junta. A morale-raising interlude came in 1978 with the holding of the football World Cup, which the hosts won.

In 1985, after the Falklands debacle brought the military regime to an end, Videla and the other junta members were tried for human-rights violations. He received a life sentence for multiple murder, kidnap, torture and theft, but was pardoned, with the others, by President Carlos Menem five years later.

Videla did his best to sink into quiet obscurity, leading an austere existence marred only by occasional outbursts against him by enraged passersby who recognised him in the street. But it was not to last. An investigation sparked by a demand from the "Grandmothers of the Plaza de Mayo" into the systematic theft of babies born to political prisoners led to court rulings that put an end to his immunity.

In 1998, a federal judge ordered him to stand trial for the illegal "appropriation of minors", a crime not subject to a statute of limitations, and excluded from amnesty laws. He went briefly to prison and was then placed under house arrest on account of his age. It is estimated that more than 500 young children and babies were illegally adopted, and their identities changed, during the so-called "dirty war". Many were taken by the families of the military themselves.

In March 2004, the German government said it had requested the extradition of Videla and two other leading figures in the dictatorship, in a case involving the disappearance of around 100 German citizens. Six months later, the former dictator was one of 18 retired officers charged in connection with the Condor Plan, a joint intelligence operation by South American dictatorships to kidnap and murder their opponents whichever country they might be in.

As he had done ever since the human-rights trials began in 1985, Videla refused to recognise the legitimacy of the court proceedings and declined to testify. It took till March 2013 for the trial to start, with the former president one of 25 defendants.

In 2007, a court threw out the amnesty granted by Menem, and in 2010 Videla received a life sentence for the torture and murder of 31 prisoners "shot while trying to escape" after the 1976 coup. In July last year, he received a 50-year sentence for masterminding the stealing of the newborn children from political opponents, and the killing of their mothers, now seen as a deliberate policy of the regime.

Paradoxically, he was a man who liked nothing better than to follow rules and routines. Although he had no scruples about violating the right to life, he was a fanatic about regulations. During his five years of military detention, it is said, he had in his possession the key to the door, and freedom. Yet he never used it.

He and his wife, Alicia Hartridge, had seven children.

• Jorge Rafaél Videla Almorozo, junta leader, born 2 August 1925; died 17 May 2013