Judge Barry had served on the federal bench in New Jersey, a position she was credited with obtaining with the assistance of Mr. Trump’s lawyer, Roy M. Cohn, during President Ronald Reagan’s administration in the 1980s.

She retired in 2019 after becoming the focus of a court investigation stemming from a New York Times investigation into the Trump family’s tax practices.

Maryanne Trump Barry, a former federal judge and the older sister of Donald J. Trump, served as both a protector and a critic throughout their lives. She has passed away at the age of 86.

She died at her residence on the Upper East Side of Manhattan, as reported by three sources familiar with the situation. Two of them mentioned that the police were called to her home early on Monday morning.

None of the sources provided a specific cause of death, and they all requested anonymity. A spokesperson for Mr. Trump did not respond to a request for comment.

According to confidants, Mr. Trump appeared to value his eldest sister’s advice more than that of most others.

However, their relationship faced a significant strain in the final year of his presidency when their niece, Mary L. Trump, who was promoting a memoir about their family, released recordings of her aunt expressing harsh opinions about the president.

A Republican, Judge Barry received her appointment to the District Court in New Jersey from President Reagan in 1983. She was subsequently elevated to the Court of Appeals for the Third Circuit by President Bill Clinton in 1993. She was also the widow of John J. Barry, an experienced trial and appellate lawyer in New Jersey.

She retired from her judicial position after The New York Times uncovered questionable tax strategies employed by the Trump family during the 1990s to bolster the inherited wealth of Mr. Trump and his siblings. The Times’ investigation revealed that Judge Barry not only financially benefited from most of these schemes but was also in a position to influence her family’s actions.

At that time, she had held the title of inactive-senior judge for two years. Her retirement rendered the court investigation irrelevant, as retired judges are not subject to judicial conduct rules.

Judge Barry’s candid criticisms of her brother surfaced through a series of audio recordings secretly captured by Mary Trump in 2018 and 2019 while Ms. Trump was working on her book “Too Much and Never Enough: How My Family Created the World’s Most Dangerous Man” (2020). The audio recordings, made available to The Washington Post, contained critiques that exceeded the already caustic comments featured in Ms. Trump’s book.

In one of the recordings, Judge Barry remarked, “His goddamned tweet and the lying — oh, my God. I’m talking too freely, but, you know. The change of stories. The lack of preparation. The lying.”

At another instance, she expressed, “All he wants to do is appeal to his base. He has no principles. None.” She added, “It’s the phoniness and this cruelty. Donald is cruel.” “You can’t trust him,” she concluded.

In 2020, Mary Trump initiated a lawsuit accusing the president and his siblings of swindling her out of her inheritance. She asserted that, for the Trumps, “fraud was not just the family business — it was a way of life.”

The White House responded by dismissing Ms. Trump’s allegations as self-serving.

Mr. Trump, 77, who is currently the leading candidate for the Republican presidential nomination despite facing multiple criminal charges in four cases, has experienced several personal losses in recent years.

His younger brother, Robert, passed away in 2020, and the president held a White House funeral service in his honor. His first wife, Ivana Trump, passed away last year. Another brother, Fred Jr., died at the age of 43 in 1981. Judge Barry was the eldest among the Trump siblings.

Maryanne Elizabeth Trump, born on April 5, 1937, in New York City to Fred and Mary (McLeod) Trump, was a granddaughter of German immigrants. Her father, a real estate magnate and the source of the family’s fortune, developed numerous apartments in Brooklyn and Queens, while her mother hailed from Scotland.

The Trump family resided in the Jamaica Estates neighborhood of Queens. Judge Barry once reminisced, stating, “I realized my father’s success for the first time when I was 15, and a friend said to me, ‘Your father is wealthy.’ We enjoyed privileges, but I was unaware of it.”

She received her education at the exclusive Kew-Forest School in Queens and obtained her bachelor’s degree from Mount Holyoke College in Massachusetts in 1958. In 1962, she earned a master’s degree in public law and government from Columbia University.

After spending 13 years as a homemaker, she enrolled in law school at Hofstra University on Long Island, where she served as the editor of its law review. She completed her legal studies in 1974 and embarked on a career in government, working as an assistant federal prosecutor in New Jersey. From 1981 to 1983, she held the position of First Assistant United States Attorney, making her one of the highest-ranking women in a federal prosecutor’s office at the time.

Her marriage to David Desmond in 1960 ended in divorce in 1980. She subsequently married Mr. Barry in 1982, who passed away in 2000.

In addition to her brother, Maryanne is survived by her younger sister, Elizabeth Trump Grau, and a son from her first marriage, David William Desmond.

She gained a reputation as a stern judge. Judge Barry declined a plea bargain that could have released two detectives accused of shielding a drug dealer; they were subsequently brought to trial and found guilty. She ruled in favor of a Gambian refugee and criticized the magistrate who had questioned his asylum application. The magistrate was later dismissed from their position.

In 2000, Judge Barry authored the majority opinion in an appellate court ruling that invalidated a New Jersey ban on late-term abortions, arguing that it was ambiguously formulated and imposed an excessive burden on a woman’s constitutional right to privacy in making medical decisions.

Despite her strict demeanor on the bench, Judge Barry recommended that women adopt a slightly more lenient approach to the issue of sexual harassment.

“While I wholeheartedly condemn the sexual harassment of women,” she conveyed to the Interagency Committee on Women in Law Enforcement in 1992, “it appears that every old sexy joke, every flirtation, is being recalled, revised, and reevaluated by some women as sexual harassment. Many of these allegations are, by any standard, trivial.”

In 2004, Justice Sandra Day O’Connor of the Supreme Court bestowed upon Judge Barry an award presented by the Seton Hall University School of Law, recognizing women who excel in law and public service.

Upon accepting the award, named in honor of Justice O’Connor, Judge Barry remarked, “I extend a message to women everywhere: remember the challenges faced by trailblazers like Justice O’Connor in their early careers. Despite graduating with top grades, she had to take a position as a legal secretary. Let’s reflect on how far we’ve come.”