Dr. Jonathan Fine was director of the North End Community Health Center in 1981 when he received a phone call that changed his life and inspired him to save the lives of untold others. Secret police had kidnapped three physicians in Chile during the Pinochet regime. Would he go and help investigate?

“When I went on that mission, I met the most courageous people I’d ever met in my life. They were people who had been tortured by the police, and they were risking imprisonment and death and terrible beatings,’’ he recalled a decade later. “I was so deeply moved. I said, ‘I must do something.’ ’’

Helping secure the release of those doctors was just the beginning. Dr. Fine, whose health had been declining when he died at 86 in his Cambridge home Wednesday, went on to help found Physicians for Human Rights, which grew into a worldwide advocacy organization.

Over the past three decades, the organization has investigated and documented the medical effects of war crimes and mass atrocities in more than 60 nations around the world — in its early days often with Dr. Fine leading the way, bearing witness to abuses in places such as Iraq and South Korea.

“We’ve just got to have the facts. Once you have the facts, you can take action,’’ he told the Globe in 1991, and that action included working with other organizations to lobby governments and courts worldwide to address and stop torture and killing.

Sometimes interviewing victims one-on-one, and other times exhuming and examining bodies in mass graves, Physicians for Human Rights has documented abuses including the use of chemical weapons against Iraqi Kurds, the prevalence of sexual violence in war zones, and all manner of torture. It shared the 1997 Nobel Peace Prize as one of the organizations that participated in the International Campaign to Ban Landmines.

Dr. Fine “was one of the seminal figures who launched an entire movement of doctors and other health professionals bringing their expertise, all the tools they have, to the human rights struggle,’’ said Susannah Sirkin, director of international policy for Physicians for Human Rights, which now is headquartered in New York City, and has offices in Boston.

“Jonathan was not only fearless himself, but he instilled this passion in us to defy convention, to do what’s necessary. He was an inspiration,’’ said Dr. Howard Hu, a professor of environmental health, epidemiology, global health, and medicine at the University of Toronto’s Dalla Lana School of Public Health, where he is the founding dean.

Hu first got to know Dr. Fine when they traveled to South Korea 30 years ago to document the military’s excessive use of tear gas against student demonstrators. Dr. Fine, Hu added, “created an organization that has now expanded into this fantastic enterprise that uses health and medicine as leverage to shed light on potential human rights abuses, and uses the tools of evidence and objectivity.’’

Key experiences from childhood onward kept pointing Dr. Fine toward human rights advocacy. He was born in Boston, a son of Jacob and Anna Fine.

When Dr. Fine was about 7, his father — the longtime chief of surgery at Beth Israel Hospital — gave him a few dollars to send to an organization that helped blind children in China. “It was the first time that I learned about people far away,’’ Dr. Fine said in the 1991 Globe interview. “It was the beginning of my interest in people who you can’t see, but you know are in need. That has stayed with me my whole life.’’

He graduated from Roxbury Latin School, received a bachelor’s degree from Swarthmore College, and was finishing studies at Yale School of Medicine when he was awarded a Fulbright grant to study health needs in India. “That was a seminal event for me,’’ he recalled. “I became interested in poverty overseas and in injustice. It led to a lifelong concern with international health and development.’’

Dr. Fine, who also has a master’s in public health from the Johns Hopkins School of Public Health, subsequently was an adviser for the US Agency for International Development in Washington, D.C., and Peru. Back in Boston, he was appointed the city’s deputy commissioner for community health services before directing the North End clinic.

His marriage to Edith Witty, with whom he had three children, ended in divorce. She was a longtime judge, serving on courts including the Massachusetts Appeals Court. Judge Fine died in 1995.

Dr. Fine’s second marriage also ended in divorce, as did his third marriage, to Patricia Busto, an immunology researcher who lives in Watertown.

“It’s almost as if he was never away from his work,’’ said his daughter Dr. Annie Fine of Brooklyn, N.Y. She added that “as a father, he was incredibly energetic and enthusiastic about things,’’ passionately introducing his family to numerous pursuits, including cross-country skiing long before it became a popular pastime. He also “really instilled in all of his children a profound sense of duty to fight injustice, and we all have,’’ she said.

In 1977, Dr. Fine cofounded a bicycle coalition in Boston. He began commuting to work by bike and insisted on selling the family car. He later sold his house near Fresh Pond in Cambridge to help finance his early human rights endeavors. He initially founded the American Committee for Human Rights, which addressed a broader range of issues, before focusing more closely on the goals of his new organization, Physicians for Human Rights, launched in 1986. Persuading the public of the work’s importance, let alone getting officials to act, was always a challenge.

“As a species we have learned little about humanitarianism,’’ Dr. Fine said in 1982, just months after his first human rights mission to Chile.

In 2014, Dr. Fine married Chris Connaire, who formerly ran People’s Theater, a racially integrated theater group in Cambridge, and who is active in Cambridge’s Quaker community.

In addition to his wife, daughter, and former wife he leaves his other daughter, Elizabeth of Brooklyn, N.Y.; a son, Grant of Orinda, Calif.; and seven grandchildren

A memorial service will be held at 2 p.m. March 3 in the Friends Meeting House in Cambridge.

In the last dozen years of his life, Dr. Fine helped found Bedside Advocates and At Your Side, two organizations that helped fragile or elderly patients navigate the health care system.

“A man like Jonathan, the US needs millions like him,’’ Jose Amado, one of the patients he personally assisted, told the Globe in 2007.

Dr. Fine will be best remembered, however, for his human rights work, where he helped pioneer studying abuses that affected large groups or entire populations — in war, for example — rather than one individual case at a time. He also championed the use of epidemiology and population-based science to recount the horrors people suffer.

“He told those stories incredibly powerfully,’’ Sirkin said. “He had a deep understanding, as a physician, for the trauma that endures beyond the initial torture.’’

At board meetings, Hu recalled, Dr. Fine and Dr. Jack Geiger, a founder and early president of Physicians for Human Rights, would often open with a reminder of why abuses must be scrupulously documented. “Statistics,’’ they’d say, “are human beings with the tears wiped away.’’

Bryan Marquard can be reached at bryan.marquard@globe.com.