José Zalaquett, a Chilean lawyer who was jailed and ultimately expelled from his country for his efforts on behalf of political prisoners and “disappeared” people during the Pinochet dictatorship, a campaign that brought him international renown as a champion of human rights, died Feb. 15 at his home in Santiago. He was 77.

His death was announced by Amnesty International, where he had served as chair of the international executive committee and later as deputy secretary general. The cause was complications from an atypical parkinsonism disorder, said his wife, Dianora Contramaestre.

Mr. Zalaquett — known to friends as Pepe — devoted nearly his entire adult life to the cause of human rights, particularly in his home country, where Gen. Augusto Pinochet led a dictatorship from 1973 to 1990. Pinochet rose to power by overthrowing the democratically elected Marxist government of Salvador Allende, who died by suicide as the Chilean air force bombed the presidential palace, known as La Moneda, in Santiago.

“For people abroad it is hard to evoke the equivalent — like bombing the White House or Buckingham Palace,” Mr. Zalaquett recalled to the London Guardian years later. “They notified the whole country in a brutal way that they mean business and they will not stop at anything. But even then we thought democracy would be restored in a few years. No one would have guessed 17 years.”

Mr. Zalaquett had served in the Allende government before accepting a university post that he held at the time of the coup. He quickly joined the vanguard of lawyers and other activists who sought to provide legal and moral support for victims of government repression.

Estimates of the number of killings and “disappearances” in Chile during the Pinochet era ranged between 3,000 and 4,000. Tens of thousands of political opponents were arrested, tortured and imprisoned.

Mr. Zalaquett became chief counsel of the Committee of Cooperation for Peace in Chile, an interfaith group founded to aid political prisoners and their families.

“There was always a secret police car watching over anybody who was going in and out, out in the streets, and inside there were lawyers and priests and nuns and political people taking testimonies of people whose families had been kidnapped and taken to secret prisons,” John Dinges, a veteran foreign correspondent in Latin America and author of the book “The Condor Years: How Pinochet and His Allies Brought Terrorism to Three Continents,” said in an interview.

“It was an amazingly fraught time, and these people were the heroes of it,” Dinges continued, citing Mr. Zalaquett as chief among them.

He credited Mr. Zalaquett with devising the strategy by which the committee and later the Vicariate of Solidarity, a Catholic successor organization, tracked reports of arrests, kidnappings, killings and disappearances.

However scant their hope of government recourse, the groups used the existing legal system to assiduously record abuses, forming a paper trail that became a critical tool for journalists, human rights workers, government investigators and victims’ families during and after the Pinochet era.

“The fact that you had an institution inside a dictatorship that was able to provide you ironclad, solid information was tremendously important,” Dinges said, “and that was one of the things that Pepe and people like him were responsible for.”

Mr. Zalaquett was arrested at least twice, imprisoned for three months and ultimately exiled in 1976 after he met with visiting U.S. congressmen. According to an account from Amnesty International, he left Chile “with two military officers walking him all the way to his plane, where they sat him down and buckled his seat belt.”

He lived for a period in Europe before settling in Washington, continuing his advocacy work through organizations including Amnesty, Americas Watch and the Ford Foundation.

In 1986, he returned to Chile, where Pinochet, while remaining army commander and a senator for life, was succeeded by President Patricio Aylwin in 1990. In the early 1990s, Mr. Zalaquett served on a national truth and reconciliation commission established to provide an official reckoning with the abuses of the Pinochet era.

The commission’s final report, running 1,000 pages, probed every disappearance and killing that had taken place during the years of military rule and unrest and was hailed as an example for panels including the South African Truth and Reconciliation Commission set up after the fall of the racist apartheid government.

“The release of the truth commission’s findings . . . had an electric effect” in Chile, Charles Krauthammer, a Washington Post columnist and regular chess partner of Mr. Zalaquett’s, wrote in a 1994 commentary.

“To the victims, particularly the ‘disappeared,’ it gave identity, a resurrection in dignity in the national consciousness. To the victims’ families, it gave the balm of knowledge and the repose that comes from a final accounting. But perhaps most important, it gave the country a catharsis.”

A point of particular contention was the question of whether to include in the report the names of alleged perpetrators of specific violations. In the end, the commissioners decided against including their identities, a position Mr. Zalaquett supported because the panel was not a judicial body.

“To name culprits who had not defended themselves and were not obliged to do so would have been the moral equivalent of convicting someone without due process,” wrote Mr. Zalaquett, who was credited with composing much of the report. “This would have been in contrast with the spirit, if not the letter, of the rule of law and human rights principles.”

Besides, he once remarked to the Los Angeles Times, “there is no perfect justice on this Earth.”

José Fernando Zalaquett Daher was born in Antofagasta, a port city in northern Chile, on March 10, 1942. His father was a merchant, and his mother was a homemaker.

Mr. Zalaquett studied law at the University of Chile, where later, after his return from exile, he helped lead a center for human rights. Years after the fact, he recalled his support for Allende with conflicted emotions.

“I was looking at this footage from 30 years ago and I thought ‘Were we that crazy?’ ” he told the Guardian. “We thought the road to socialism was inevitable. We had this naive belief that because the winds of history were blowing in our direction, somehow we would be taken to a safe harbor.

“A mixture of the spirit of the sixties, a thirst for justice, well-intentioned irresponsibility and naivete, and you get what we were,” he continued. “Honestly speaking, we have very mixed views about Allende. We respect his self-immolation and his heroism. He was very well-meant but a terrible administrator. We knew the government was doomed and it was just a question of time.”

Mr. Zalaquett’s marriage to María Pía Fuentealba ended in divorce. Survivors include Dianora Contramaestre, his companion for 29 years and his wife since 2003, of Santiago; two daughters from his first marriage, Daniela Zalaquett and Valeria Zalaquett, also of Santiago; four sisters; a brother; and four grandchildren.

Mr. Zalaquett, who in 1990 received a MacArthur Foundation “genius” grant for his human rights work, was a past chairman of the Inter-American Commission on Human Rights, which is an arm of the Organization of American States.

Alexander Wilde, a former director of the Washington Office on Latin America, a human rights advocacy group, wrote in an email that with his “remarkable lucidity, clarity, subtlety and persuasiveness,” Mr. Zalaquett “showed that ‘human rights’ could have real effects beyond what had long remained fine aspirations expressed in little-known international declarations and treaties.”

“He had bedrock convictions about the universality of human rights,” Wilde observed, “but he also understood and accepted the reality and inevitability of politics in the world.”

The experience of the Pinochet era, Mr. Zalaquett once told ABC News, persuaded him that “inside every one of us there is the potential for the beast,” and that “out of any human beings — . . . except for a few of them — you can make a torturer.”

But he also saw in each person the “potential for the most noble acts.” His friends were quick to note that his life was not entirely consumed by matters of imprisonment and torture and disappearances. Besides chess, he loved art, especially the works of Paul Klee, and music.

Claudio Grossman, a former dean of American University’s law school, was a law school classmate of Mr. Zalaquett’s and a fellow Chilean exile during the Pinochet era. He said he saw in his friend “unlimited optimism that at the end democracy will prevail and human rights will prevail,” that “there was something good in everyone and that . . . better days will arrive.”