A.W. Richard Sipe, a priest and psychotherapist whose research on celibacy and the Roman Catholic Church’s sex abuse scandal earned him popular renown and official scorn, died Wednesday in his Mount Soledad home. He was 85.

His son, Dr. Walter Sipe, attributed the cause of death to multiple organ failure.

Sipe’s work was instrumental in the 2002 Boston Globe’s “Spotlight” reports, which led to a worldwide revolt against Catholic clergy who had sexually assaulted children. After initial denials, church leaders slowly agreed to reforms.

In 2017, though, Sipe argued that the problem persisted, fueled in part by the secret sex lives of Catholic clergy.

“From the top down,” he told the Union-Tribune, “it hasn’t changed.

“This is my thesis and I am going to hold to it because I think it has proved out — the problem is at the top. If you have people at the top who are sexually active and they are in charge of people who are acting out, you can’t afford to expose that, lest you be exposed.”

After the Vatican released Sipe from his vows of celibacy and obedience in 1970, he married a former nun, Dr. Marianne Benkert. In 1998, the couple moved to La Jolla where their only child, Walter, was enrolled in the UC San Diego School of Medicine.

In a quiet study decorated with an 11th century image of Christ welcoming souls to paradise, he continued his studies of the sex lives of Catholic clergy. At any one time, he estimated, 50 percent of priests are involved in sexual relationships, while 6 percent are sexually abusing children.

When the Globe’s Spotlight team learned of his research, they flew Sipe and his wife from San Diego to Boston, where he briefed the reporters on the subject.

He went on to become a renowned expert witness, testifying in about 250 cases brought against Catholic priests accused of rape and other sexual crimes. He was a much sought-after speaker on college campuses, in public forums and in conferences addressing this crisis.

Within the offices of the Roman Catholic Diocese of San Diego, though, he was often unwelcome.

"I've been blackballed, " he said in 2015. "Bishop Robert Brom sent his chancellor here to say I was not welcome in the chancery. If I came, it would only be in the presence of a lawyer."

While he visited the current bishop, Robert McElroy, at least twice, their relationship was also rocky.

“Sooner or later it will become broadly obvious that there is a systemic connection between the sexual activity by, among and between clerics in positions of authority and control, and the abuse of children,” Sipe wrote in a letter to McElroy in 2016.

“When men in authority — cardinals, bishops, rectors, abbots, confessors, professors — are having or have had an unacknowledged-secret-active-sex life under the guise of celibacy, an atmosphere of tolerance of behaviors within the system is made operative.”

Walter Richard Sipe was born on Dec. 11, 1932, in Robbinsdale, Minn. He was the fourth of 10 children of Walter C. Sipe, who owned several gas stations, and Elizabeth (Altendorf) Sipe, a homemaker.

His family were observant Catholics, and from an early age he was entranced by the church. After attending a high school and a college run by Benedictine monks, he became a monk himself. In 1959 he was ordained a priest. (He took the name Aquinas, after the theologian St. Thomas Aquinas, when he became a brother and added the initial A. in his name.)

But it was not long before he realized that just below the surface of the church lay secrets that its hierarchy protected.

In his first posting, to Cold Spring, Minn., to work as a high school counselor, he heard in the confessional about priests who were sexually involved with other priests, priests who had girlfriends, and even priests who were involved with minors, he said in an interview in 2008 for a documentary film, “Sipe: Sex, Lies, and the Priesthood,” which is to be released this year.

He also learned that his predecessor had abused girls. Yet these men remained in good standing with the church, he said.

“So I asked myself, What is this celibacy, and how is it practiced by those people who claim to be celibate?” he said in the interview, giving voice to the research question that would animate his career.

In 1967, he became the director of family services at the Seton Psychiatric Institute in Baltimore, a treatment center where bishops sent problem priests. As he got to know the troubled men, he said, some revealed that they had been abused by clergymen themselves. He also heard stories about how church leaders had been dismissive of reports of abuse.

He began formally collecting data, seeking patterns. He was encouraged by Margaret Mead to conduct his studies in an ethnographic fashion, describing the customs and culture of his tribe — in this case, Catholic priests.

Twenty years after leaving the priesthood, he published “A Secret World: Sexuality and the Search for Celibacy.” Assisted by his wife, a psychiatrist, the landmark study drew on case files and 25 years of interviews with hundreds of sexually active priests, as well as victims of clergy sex abuse.

Sipe had assumed that his study would be welcomed by bishops, Dr. Benkert Sipe said. Instead, he was blackballed in some dioceses.

“When he wasn’t listened to, and wasn’t believed, it was really hurtful to him, because he cared about the church,” she said.

Further studies have supported Sipe. In 2017, an investigation by the Australian Royal Commission found that 7 percent of priests in the Australian Catholic Church had been accused of sexually abusing children from 1950 to 2010. A study commissioned by the American bishops in 2004 put the percentage at 4 percent.

“He lived long enough to see many of his predictions come true,” said Phil Saviano, a clergy-abuse activist and friend.

Still, accountability for bishops continued to elude Sipe, frustrating him.

“I defy you to find where the system has changed,” he said in 2008. “Bishops are not accountable, they can — and do — do what they want.”

In recent weeks, a wider swath of the church appeared to be coming around to accepting that statement. Sipe had been warning on his website about the sexual activities of Cardinal McCarrick since 2008. After a substantiated report of abuse was revealed in June, followed by more allegations, some of the nation’s leading bishops began calling for reforms in how allegations against bishops are investigated.

Though Sipe had devoted his life to understanding the issues of celibacy and abuse, the deeper question of why the problem could persist unaddressed for so long still eluded him, said the Rev. Tom Doyle, a friend and longtime advocate for abuse victims.