A convoy of Brazilian army troops, tanks and other vehicles pauses on the way to Rio de Janeiro on April 1, 1964, after conspirators in the country’s military high command overthrew the government and forced Brazilian President Joao Goulart to flee. (AP)

Under a 1979 amnesty law, no one has ever been tried for the human rights abuses committed during Brazil’s dictatorship. Although some victims have spoken about the horrors of that dark time, it seemed many Brazilians preferred to forget.

But as the country marks the 50th anniversary this week of the coup that brought the military to power, the dictatorship is at the center of a national debate about what happened and what it means today.

“People are reflecting on the past and teaching a new generation of Brazilians about the dictatorship,” said James N. Green, a professor of Brazilian history and culture at Brown University.

No official commemorations were planned, but unlike in previous years, film screenings, lectures and discussions have been organized in major cities to mark the anniversary.

At a news conference Monday in Brasilia, the capital, President Dilma Rousseff remembered the victims of the coup, the BBC reported. “Our present day requires that we remember and speak about what happened. We owe this to those who died and disappeared, owe it to those who were tortured and persecuted, owe it to their families,” the BBC quoted her as saying.

Separately, Justice Minister José Ed­uardo Cardozo issued an official apology to the victims of the military government, the BBC said.

Rousseff, a former member of a left-wing guerrilla group, was among those imprisoned and tortured. She has never spoken publicly about the details of her experience.

The country’s truth commission is increasingly generating interest as former officials defend their actions nearly three decades after the dictatorship ended. In testimony this month, former colonel Paulo Malhães admitted torturing and killing members of guerrilla groups and mutilating their bodies. He noted that the tactics successfully quashed armed resistance. “When you cut off the head of a snake, you finish off the snake,” he told the commission.

Some victims say echoes of the dictatorship remain — in the heavy police response to protests that swept Brazilian cities last year, in police violence in Rio’s slums and in a military operation that began Sunday to pacify Mare, one of the city’s most dangerous areas.

Although police shootings are common in the slums, or favelas, officers are rarely punished. According to Amnesty International, Brazilian police are responsible for about 2,000 deaths a year.

“Twenty-one years of a mentality like this made the country go backwards,” said Cid Benjamin, a former militant whose memoir, “Thanks to Life: Memories of a Militant,” was published in October. “Brazil does not want to go back to the dictatorship, in any way.”

Benjamin, once a member of a left-wing guerrilla group, was arrested in 1970 after participating in bank robberies, armed actions and the kidnapping of the U.S. ambassador, Charles Burke Elbrick. In jail, Benjamin said, he was beaten and tortured, tied naked around a pole “like a roast chicken.”

The armed resistance to the dictatorship failed to mobilize popular support. “It was a political error, although it was a legitimate action,” Benjamin said, adding that he did not feel any anger toward his torturers. “I don’t hold on to rancor and resentment.”

‘A long night of darkness’

In the year before the coup, left-wing President João “Jango” Goulart embarked on a program of social reform. A speech he gave in Rio on March 13, 1964, promising dramatic changes sparked fears of a communist takeover.

On March 19, hundreds of thousands in Sao Paulo joined the anti-reform Family March With God for Liberty, which led right-wing military elements to believe they could depose Goulart without sparking a civil war. They were proved right.

Between 300 and 400 government opponents were killed and thousands were tortured during the 21-year dictatorship. And although far more people died under dictatorships in Argentina or Chile, the period is seen here as a traumatic era in Brazil’s history.

“Democracy was violated in a way that left an enormous scar on Brazilian citizenship,” said Quitéria Teixeira, 34, an unemployed single mother in the city of Teresopolis.

Brazil is facing increasing pressure to revise its amnesty law so that perpetrators can be held accountable.

“The only way to close this chapter is to do justice for people who suffered the consequences of the dictatorship,” said Atila Roque, executive director of Amnesty International Brazil, which is launching a campaign to change the law.

Last week, a Facebook page run in Rousseff’s name by her Workers’ Party changed her profile photo to an iconic, dictatorship-era image. “On March 31, 1964, Brazil fell into a long night of darkness,” the text on the page reads. A presidential spokesman said opinions on the Facebook page cannot be taken as Rousseff’s. But some in the news media interpreted the page as an acknowledgment of the anniversary.

Recent police violence

Demands are growing louder for the demilitarization of Brazil’s street police force, which is called the military police and run like an armed forces unit. The Inter-American Commission on Human Rights recently began a hearing in Washington on human rights and social protest in Brazil, with evidence presented of police violence during 2013 demonstrations. The death this month of a woman who was shot during a police action in a Rio favela led to a public outcry. Claudia Ferreira, 38, was put in the back of a police vehicle. A video that went viral shows her falling out and being dragged along the highway on the way to a hospital. The mother of four was pronounced dead on arrival. Three officers were suspended.

Critics say the incident is another example of police impunity.

“We have the requirements of the dictatorship until today,” said Marcos Arruda, 73, a former militant who was arrested in 1970, tortured, and freed in 1971.

Meanwhile, Brown University and the State University of Maringa in Brazil have begun releasing thousands of State Department and declassified CIA documents that show the extent of U.S. logistical and political support for the coup.

On a recent day, Alina Assis, 29, a student in Rio, purchased a magazine with a cover story about the U.S. involvement. “It is not a surprise that the U.S.A. supported it,” she said. “But it is a surprise that it is in a Brazilian magazine.”