WASHINGTON — As a pioneering psychological profiler for the Central Intelligence Agency and later as a consultant, Jerrold Post plumbed the lives, leadership styles and, at times, the mental illness of foreign heads around the globe. Over decades, his expertise and instincts were greatly in demand, especially at the White House.

The Harvard-trained psychiatrist advised former president Jimmy Carter about how best to negotiate with Menachem Begin and Anwar Sadat before the Camp David Peace Accords. He explained Sadat’s “Nobel Prize Complex” – his desire to be remembered as a great leader – and Begin’s biblical preoccupation and obsession with detail.

Post warned about labeling Saddam Hussein simply as “the mad man of the Middle East,” lest it mislead political leaders into thinking Hussein was unpredictable, when in fact he was not. As an expert in the psychology of terrorism, Post produced psychological profiles of suicide bombers in Israel and opined on the corporate leadership style of al-Qaida leader Osama bin Laden.

And yet in late 2019 – a year before his death on Nov. 22 of COVID-19 at the age of 86 – Post found himself doing what at one point would have been unthinkable: publishing a book about the alarming psychological makeup of an American president.

In writing “Dangerous Charisma: The Political Psychology of Donald Trump and His Followers,” Post risked violating the American Psychiatric Association’s “Goldwater Rule,” which forbids the diagnosis of public figures without full evaluation and consent.

“He was a Life Fellow of the APA, but he said if they kicked him out, he didn’t care,” said his wife, Carolyn Post. “He felt it was that important and that psychiatrists have a duty to warn.”

By then, Post had had a storied two-decade career as founding director of the CIA’s Center for the Analysis of Personality and Political Behavior. He then used his expertise to found Political Psychology Associates, a research and consulting firm that specialized in industrial espionage, counterterrorism and leadership assessment. All along, he lectured as a professor at George Washington University, wrote 14 books and continued to see patients in a private practice he ran out of the basement of his Bethesda, Md., home.

His career success, his family said, was a reflection of an insatiable, roving curiosity and a probing empathy for his fellow humans – qualities that also made him a highly engaging friend and a nurturing husband, father and doctor.

He devoured books about politics and history, with a penchant for biographies by Doris Kearns Goodwin and David McCullough. He traveled the world with his family and – always drawn to the human – took lovely candid photographs of people off the beaten path that won national awards, his family said. He did not hang back as tourists tend to, but engaged people in his humble way about their lives. On a trip to Mexico with his daughter Cindy Post he drove off the main road, where he came upon some male villagers playing a board game near a cliff overlooking the ocean. He gestured to join them, they offered drinks, and he snapped away.

“He always wanted to know, What are the people about and what is their world?” said Cindy, 58, a clinical psychologist in Silver Spring. Her father “was kind of a whirling dervish. . . . He was the kind of person who would think, ‘There are 24 hours in a day. Can we fill 23 of them?”

He zipped from place to place in his beloved convertible sports cars – a favorite was a green Austin-Healey – with a signature driving cap atop his head.

Post was born in 1934 in New Haven, Conn. His father sold movies to theaters and his mother worked as a bookkeeper, taught painting, and made and sold pottery. He put himself through nearby Yale University for his undergraduate degree and then medical school. He received his postgraduate psychiatric training at Harvard Medical School and the National Institute of Mental Health.

He was an accomplished improvisational jazz pianist who could also play almost any tune by ear, his family said. For anniversaries, birthdays and other special occasions, he would write new lyrics for Gilbert and Sullivan show tunes and, with Carolyn, serenade friends and relatives.

He was witty, too, and loved word play. Post was a member of a lunch group of GWU professors dubbed IOTA, which stood for the International Order of Twisted Aphorisms. Members would write puns and aphorisms to bring to the meetings. When a nurse asked him before the recent election who the president was – standard practice with elderly patients – he replied sardonically: “Unfortunately, we don’t have one at the moment.”

Post was a fiercely competitive backgammon player – and schooled his daughter Meredith Gramlich from childhood on the fine points of the game on a custom hand-carved board from Israel. In the twilight of his life, he reassured 52-year-old Gramlich proudly, “I never threw a game for you.”

He was also a faithful father to daughter Kirsten Davidson, 49, who is blind and intellectually disabled, greeting her in a special way every morning and signing off to her each night.

At the CIA, Post was able to marry his triple passions of psychiatry, history and politics by founding the agency’s Center for the Analysis of Personality and Political Behavior. The work of the center, an interdisciplinary behavioral sciences unit that assessed foreign leaders for the president and other senior officials, was groundbreaking, said Nicholas Dujmovic, a longtime CIA historian who retired from the agency in 2016 and is now an assistant professor of politics at Catholic University of America.

“Post made it obvious through his work that we need to have professionals involved in assessing the health and psychology of foreign leaders,” said Dujmovic, who as an editor of the president’s daily briefings at the CIA said he frequently encountered Post’s “legacy” in briefing contributions.

He said he was surprised to learn that among Post’s many honors – including the Intelligence Medal of Merit in 1979 after his role in the Camp David Accords – he is not listed as one of the CIA “Trailblazers,” who made a significant impact on the agency’s history. He believes that could be due to “snobbery” within the agency during Post’s time there that distrusted the practice of psychological analysis, especially when conducted from afar.

Carter contradicted that notion, Dujmovic noted, openly crediting the role of Post’s team in the success of the historic peace agreement. Carter “basically said ‘I spent two weeks with these men and I wouldn’t change a word of [Post’s] assessments,’ ” Dujmovic said.

In his last effort to psychologically profile a leader, Post trained his expertise on Donald Trump. In “Dangerous Charisma,” co-authored with Stephanie Doucette, Post described Trump as a destructive charismatic leader with the traits of a classic narcissist – such as grandiosity, lack of empathy, hypersensitivity to criticism and no constraints of conscience. But Post also probed Trump’s symbiotic relationship with his followers, and theirs with him.

“The dangerous, destructive charismatic leader polarizes and identifies an outside enemy and pulls his followers together by manipulating their common feelings of victimization,” Post said in a December 2019 interview.

Were he to lose the election, Post said a year ago, “I think we can be assured that he will not concede early. Trump may not even recognize the legitimacy of the election.”

After the book’s publication, Post’s health took a downward turn. His kidneys had already been failing, forcing him to go for dialysis several times a week, when he suffered a stroke in July. After several months in a rehabilitation facility, Post spent his final weeks of life surrounded by family at home. On Sunday Nov. 15, he began having trouble breathing. Carolyn called 911 and an ambulance rushed him to the hospital, where he tested positive for the coronavirus. He died exactly one week later.

Visiting with her father in his waning days, Cindy Post said, she tried to help him consider the fullness of his restless life and find peace with the end.

“How do you feel about the life you had,” she asked him. “You’ve done a lot of things, you know.”

“There’s so much more to do,” Post replied.

“But can you let this be enough?” his daughter asked.

He didn’t answer, but Cindy said she could see the frustration written on her father’s face.