For many Americans, the killings that hit home hardest took place on Dec. 2, 1980, a little over eight months after the archbishop’s assassination. They are the focus of the Retro Report video. Salvadoran national guardsmen — five were eventually found guilty — murdered four American churchwomen who worked in that country with the poor. Three were Catholic nuns: Ita Ford, Maura Clarke and Dorothy Kazel. The fourth, Jean Donovan, was a lay missionary. They had been beaten, raped and shot execution-style in the head. Their nude bodies were dumped by a road. Local peasants clothed them and buried them in a shallow grave.

Robert E. White, then the United States ambassador to El Salvador, stood by as the bodies were exhumed. It was evident, Mr. White recalled for Retro Report, that the Salvadoran military was “out of control” and “would kill anybody.” But why these women? “In the eyes of the military, identification with the poor was the same as identification with revolution,” he said.

Seven weeks after those murders, Mr. Reagan took office. Mr. White did not last long in his post. He was out of step with the new administration, which supported the Salvadoran rightists. He was also dismayed by what he saw as an effort in Washington to shrug off the killings. Jeane J. Kirkpatrick, who would soon become the American ambassador to the United Nations, described the churchwomen as “political activists,” not just nuns. That was not so, Mr. White said. Alexander M. Haig Jr., the secretary of state, suggested that the women may have run a roadblock, and were killed in an exchange of gunfire. None of that was true.

In 1998, some of the convicted guardsmen said in interviews that they had acted on “orders from above.” They singled out no one. But in immigration court cases pursued in the United States, responsibility fell upon, among others, the two generals living out their lives in Florida. Nine months ago, an immigration judge in Miami ruled against General García’s continued stay in America, saying he “knew or should have known” about the atrocities that took place on his watch. Another immigration judge issued a similar assessment of General Vides in 2012, and ordered his deportation.

Until a decade ago, the concept that the United States should not be a haven for foreign violators of human rights had been applied principally to those who were part of the Nazi killing machine, many of them as death camp guards. Some made their way into this country in the first years after World War II, typically by lying about their past. But more than a dozen others, at a minimum, were invited to resettle here and given cover by United States intelligence agencies, according to recent revelations by a New York Times reporter, Eric Lichtblau. He described those men as among a thousand or more Nazis used by the agencies during the Cold War as anti-Soviet spies and informants here and in Europe.

Cases against Nazi suspects were pursued by the Justice Department’s Office of Special Investigations, which was created in 1979 but was absorbed four years ago into a new section of the department. In all, 107 were deported or stripped of their American citizenship. (On Oct. 19, The Associated Press caused a stir with a report that several dozen of those who had helped the Nazis, all quite old, were allowed to keep their Social Security benefits, a policy criticized by some elected officials and others.)

In recent years, relying on a 2004 law prohibiting human rights abusers from entering or living in this country, Washington has broadened its scope to include violators from all over. Immigration and Customs Enforcement, a branch of the Department of Homeland Security, reported last December that over the previous decade, it had obtained deportation orders for more than 640 people.

Some human rights activists say the law’s arm could be even longer in the pursuit of transgressors. Among them is Pamela Merchant, until recently executive director of the Center for Justice and Accountability. Her San Francisco-based group brought lawsuits against a broad range of accused rights abusers, including the Salvadoran generals in Florida. “I do think there’s a much stronger commitment to keep guys like this out of the country,” Ms. Merchant said, but she detected “some ambivalence” in Washington in regard to tossing out “people already here.”

Still, she acknowledged, the prevailing spirit is far different from what it was years ago. Another cliché holds that justice delayed is justice denied. But the feeling among people like Ms. Merchant is that if it means denying American sanctuary to killers and torturers, justice delayed is still justice.

CLYDE HABERMAN, a regular contributor to Retro Report, has been a reporter, columnist and editorial writer for The New York Times, where he spent nearly 13 years based in Tokyo, Rome and Jerusalem. Subscribe to our newsletter here and follow us on Twitter @RetroReport.

This article first appeared in The New York Times.