Jean Maria Arrigo, a psychologist who blew the whistle on her profession’s secret ties to the torture and abuse of war-on-terror detainees, helping expose collusion between American Psychological Association officials and Defense Department leaders after the terrorist attacks of Sept. 11, 2001, died Feb. 24 at her home in Alpine, Calif. She was 79.

The cause was complications from pancreatic cancer, said her husband, John Crigler.

A social psychologist and oral historian who focused on ethical issues in national security, Dr. Arrigo was “an unexpected and unassuming whistleblower,” said colleague Roy Eidelson, who worked alongside her in a group called the Coalition for an Ethical Psychology. She participated in peace marches in Central America during the 1980s but considered herself an introvert at heart, saying she would much rather be reading poetry than campaigning to overhaul the American Psychological Association (APA), the world’s largest professional organization of psychologists.

“What she wanted to accomplish, and what she continued to work on, was in a sense saving the profession from itself,” Eidelson said in an interview. “Making sure that ethical red lines would keep psychologists from becoming involved in things that were wrong. That’s an ongoing struggle that she now serves as an inspiration for.”

Dr. Arrigo had been studying national security issues for about a decade, interviewing intelligence experts and weapons developers about their moral concerns, before being appointed to an APA task force in 2005. The group was assembled to issue guidelines for psychologists involved in national security interrogations, in the aftermath of news reports about military and CIA abuses at overseas detention centers.

Pictures emerged showing military personnel taunting naked prisoners at Abu Ghraib prison in Iraq, and a front-page story in the New York Times documented a leaked report from the International Committee of the Red Cross, alleging that psychologists at Guantánamo Bay were involved in interrogations that were “tantamount to torture.”

Over the next decade, reporters and Senate investigators continued to document the use of “enhanced interrogation techniques,” including waterboarding, as part of a program that was run with help from two former military psychologists, James Mitchell and John Bruce Jessen.

Dr. Arrigo and her allies were horrified by psychologists’ involvement in the interrogations, which they found to be an abdication of the profession’s fundamental principle of “do no harm.” During task force meetings, they pushed to adopt stricter ethical constraints, including by following provisions of the Geneva Conventions instead of standards set by the George W. Bush administration.

But the 10-member task force, which held its meetings in secrecy, was stacked with national security insiders intent on maintaining the status quo, according to Dr. Arrigo. The group’s final report concluded that it was fine for psychologists to remain involved in interrogations and argued that their work ensured that the process was “safe, legal, ethical and effective” — language that was later shown to have been provided by officials at the Defense Department.

Convinced that the task force was “a sham,” Dr. Arrigo took her concerns to the public, sharing the group’s private correspondence and meeting notes with journalists and members of the Senate Armed Services Committee.

At the APA’s annual convention in 2007, she shocked colleagues by criticizing the task force in a speech that was recorded by the news program “Democracy Now!,” recalling how the group seemed to have an overriding concern for haste, with an aim “to put out the fires of controversy right away.”

Colleagues responded with silence, denials or highly personal criticism.

Gerald Koocher, a former APA president who was involved in the task force, wrote an open letter in which he attacked Dr. Arrigo for having “personal biases” and a “troubled upbringing,” alluding to a task force meeting in which she had discussed her contentious relationship with her father, a career Army officer who, according to Dr. Arrigo, was involved in torture while doing undercover work during World War II. Koocher also claimed that Dr. Arrigo’s father had died by suicide; in fact, he was still alive.

Over the next several years, Dr. Arrigo continued to criticize the organization’s approach to national security interrogations, alongside other dissident psychologists who argued that the organization had set aside professional ethics while seeking to expand its footprint through ties with the government and military.

Many of her criticisms were vindicated by the release of an independent review report, commissioned by the APA after the publication of Times reporter James Risen’s 2014 book “Pay Any Price: Greed, Power, and Endless War,” which alleged that the APA had effectively been providing cover for abusive interrogations.

Prepared by former federal prosecutor David H. Hoffman, the 542-page report found that the APA’s ethics office “prioritized the protection of psychologists — even those who might have engaged in unethical behavior — above the protection of the public.”

“The evidence supports the conclusion that APA officials colluded with DoD officials to, at the least, adopt and maintain APA ethics policies that were not more restrictive than the guidelines that key DoD officials wanted,” the report said, referring to the Defense Department. It added that the “APA chose its ethics policy based on its goals of helping DoD, managing its PR, and maximizing the growth of the profession.”

Later that year, the APA voted to ban psychologists from assisting in national security interrogations. The group’s ethics chief was removed from his position, and three other senior officials resigned or retired early.

“In a story full of villains, Arrigo emerges from Hoffman’s report as a hero — and a martyr,” the Guardian declared.

Dr. Arrigo was awarded the 2015 Scientific Freedom and Responsibility Award from the American Association for the Advancement of Science, which praised her “courage in continuing to stand up and speak out for the ethical behavior of members of her profession.” She was also presented with a plaque by the APA’s governing council, which called her the group’s “ethical, moral conscience” and “the finest possible role model for us in the profession of Psychology.”

“I’ve spent 10 years of my life that I wish I could have back,” she said.

The oldest of three daughters, Jean Maria Arrigo was born in Memphis on April 30, 1944. Her mother was a schoolteacher, and her father spent part of her childhood overseas, with military stints in Japan and Taiwan.

Dr. Arrigo graduated from high school in San Francisco and initially studied mathematics, receiving a bachelor’s degree from the University of California at Berkeley in 1966 and a master’s degree from UC-San Diego in 1969. She taught mathematics at San Diego colleges and universities for more than a decade while developing a growing interest in human rights, which led her to retrain as a social psychologist.

Enrolling at Claremont Graduate University, she received a master’s degree in 1995 and a doctorate in 1999. Her oral history work led to the creation of archival collections at the University of California at Berkeley in 2004 and Stanford University in 2005. Collaborating with her husband, Crigler, a composer and musician, she also adapted some of her oral histories into theater performances, which she described as attempts to “stimulate public moral discourse.”

In addition to Crigler, her husband of more than 25 years, survivors include two sisters.

When she received the APA honor in 2015, Dr. Arrigo said she was simultaneously “very touched” and “very wary,” skeptical of an organization that had been “dedicated to looking the other way” after years in which it was “interlocked with the national security establishment.”

Interviewed by Claremont the next year, she reiterated her skepticism, noting that she was not convinced that ethical issues around national security would not arise in the future. “That’s like believing that when the Russians shot down [Francis] Gary Powers’ spy plane in 1960 that the U.S. gave up espionage,” she said.