“Everything depends on the political context and political will, and I don’t see the political will in Lula’s administration,” José Miguel Vivanco, the executive director of the Americas program of Human Rights Watch, said in a telephone interview from Washington. “Politicians are rational actors. They are willing to challenge the status quo only if they have a constituency or some pressure, and I don’t know if that constituency exists in Brazil the way it does in Argentina and Chile.”

Speaking on behalf of Colonel Ustra, his wife, Joseita, declined a request for an interview with him, saying he is recovering from surgery. But in recent speeches made to military groups before his hospitalization, he suggested that he was not the human rights groups’ only target.

“I am the first, but tomorrow there will be others,” he said in a speech to an audience of more than 400 fellow officers and sympathizers at the Military Club in Rio de Janeiro in January. “I am being judged for a crime I did not commit. It is the revenge of those who were defeated in 1964, many of whom today find themselves in power.”

Colonel Passarinho said that among the people Colonel Ustra had in mind was Dilma Rousseff, Mr. da Silva’s chief of staff. As a member of an armed revolutionary group, Ms. Rousseff, then nicknamed “the guerrilla Joan of Arc,” was involved in a $2.5 million robbery in 1969 and was captured the next year, tortured and held in prison for three years.

Colonel Ustra, 74, is the founder of a group called Terrorism Never Again, formed as a counterpoint to Torture Never Again, and the author of a book, “The Suffocated Truth.” The book was intended to, in his words, “undo the myths, farces and lies to manipulate public opinion” about the period of the dictatorship. He acknowledges that some of his subordinates may have committed abuses, but he insists that he never personally participated in torture sessions. That claim has been contested by human rights groups and former prisoners.

“As commander, he not only knew what was going on, but personally tortured me when I was seven months pregnant,” said Ms. Schmidt de Almeida, a former guerrilla. “He used electricity to shock me not on the anus, mouth and genitals, which was the standard practice then, but on the hands and feet, and he beat me about the head.

“It’s not just me, but Brazilian society as a whole that is living with the consequences of that repression,” she added. “It’s a difficult thing to confront, but there have been important advances in Argentina, Chile and Uruguay, and for our own well-being, we need to resolve this issue, too.”