A flag displaying two swastikas and a Star of David appeared on top of a building on the New York University campus on Wednesday, the Police Department confirmed on Thursday.

The flag, which appeared near Washington Square Park, resembled the many purple N.Y.U. flags flying on campus buildings but was emblazoned with two swastikas surrounding a Star of David. According to the student newspaper, Washington Square News, the flag appeared about 5 p.m. and was removed roughly 15 minutes later.

The Police Department received a 911 call at 5:21 p.m. reporting harassment. When officers arrived, a man told them that a flag had been tampered with to display swastikas. An investigation remains ongoing, a Police Department spokeswoman said, and no arrests have been made.

“We are shocked and deeply troubled that this hateful symbol expressing antisemitism was raised on a flagpole overlooking Washington Square Park,” Wiley Norvell, an N.Y.U. spokesman, said in a statement. “Campus safety responded immediately to remove it, and we are working closely with the N.Y.P.D. to identify whoever is responsible.”

The flag appeared during a graduation week event known as Grad Alley, a block party where soon-to-be graduates and their families take in live music, dance performances and play carnival games. During the event, some people noticed the flag waving on top of the Steinhardt School of Culture, Education and Human Development, on a corner overlooking the park, according to the student newspaper.

The Steinhardt School was named for Michael and Judy Steinhardt after they donated $10 million to N.Y.U. to support “faculty development, doctoral fellowships and research.”

Mr. Steinhardt, a billionaire, made his money on Wall Street before becoming a major donor to N.Y.U. as well as to Jewish philanthropies. The Brooklyn Botanic Garden includes a Steinhardt conservatory, and the Steinhardt Gallery at the Metropolitan Museum of Art is also named for him. Mr. Steinhardt is one of the founders of Birthright Israel, which sends young Jewish people on free trips to Israel to bolster their connection to the country and support their Jewish identity.

The incident during the Grad Alley event followed objections to N.Y.U.’s choice of a commencement speaker. Student government leaders objected to Jonathan Haidt, a social psychologist and author, being selected to speak at the graduation ceremony and sent a letter to university officials asking them to reconsider their choice. The student leaders cited Dr. Haidt’s criticism of diversity, equity and inclusion efforts.

This is a developing story. Check back for updates.

A man accused of running a secret police station in Manhattan at the direction of the Chinese government, using it to report to Beijing on political dissidents, was convicted of illegally working as a foreign agent on Wednesday.

Lu Jianwang, federal prosecutors in Brooklyn said, opened the station with the goal of helping Chinese citizens renew their driver’s licenses while living in America. But a far more sinister aim, they said, was running the outpost as a hub to monitor outspoken critics of the Chinese Communist Party.

Mr. Lu, an American citizen also known as Harry, was accused of aiding China’s campaign of transnational repression by opening an illegal police station in Manhattan’s Chinatown neighborhood.

Mr. Lu, 64, who wore an American flag pin on his suit during the trial, did not react as the verdict was read aloud. He was supported by dozens of members of a group linked to his hometown in China.

He was “in lock-step with what the Chinese government asked him to do,” Antoinette N. Rangel, a federal prosecutor, said during her closing argument on Tuesday.

After a full day of deliberations, a jury found Mr. Lu guilty on one count of acting as a foreign agent and another of obstructing justice. He was acquitted of conspiring to act as an agent of China.

Dozens of Mr. Lu’s supporters from his church and his Chinese community organization packed the courtroom. One supporter pumped her first as the verdict on the first charge, not guilty, was read aloud, but struck a somber tone after the guilty verdicts. Mr. Lu did not change his expression.

Mr. Lu had been “held accountable for blatantly disregarding the law and our country’s sovereignty,” Joseph Nocella Jr., the U.S. attorney in Brooklyn, said in a statement. He added that his office would protect the rights of those “seeking freedom from repression and speaking out to bring democracy, reform and human rights to China.”

Mr. Lu, along with Chen Jinping, was arrested in April 2023. Mr. Chen pleaded guilty to working as an unauthorized agent of China in December 2024.

Mr. Lu was the president of the American Changle Association, a Chinese community organization and social club for people from the city of Fuzhou, like Mr. Lu. Such groups have attracted scrutiny for their persistent efforts to influence New York politics, through methods such as harassing and threatening candidates with platforms seen as harmful by the Chinese government, at the behest of the Chinese Consulate.

Mr. Lu’s brother, Jimmy, had made donations to former New York Mayor Eric Adams, who spoke at the club during an event in September 2022, days before it was raided by federal agents. In July 2022, Jimmy Li, a congressional candidate with roots in Fujian Province, which includes Fuzhou, visited the clubhouse and was endorsed by a number of the group’s leaders.

The weeklong trial showcased the Justice Department’s long-running crackdown on what it calls a global campaign by China to harass, intimidate and repatriate its political dissidents. Prosecutors depicted Mr. Lu as a willing operative of the Chinese government, eager to deepen his longstanding ties with party officials.

They presented the jury photos of Mr. Lu mingling with government officials in China, text messages in which a Chinese security official asked him for information on a prominent pro-democracy activist, and expert testimony about China’s global efforts to quell dissidents.

But Mr. Lu’s lawyer, John Carman, described the case as overreach by federal prosecutors. During his closing statement on Tuesday, he said Mr. Lu had merely been trying to help his fellow community members, Chinese Americans of Fujianese heritage.

“This isn’t spy time,” Mr. Carman said. “This isn’t international espionage. This is license renewal.”

In January 2022, Mr. Lu began working with Liu Rangyan, an official at the Chinese Ministry of Public Security, who became his official handler, prosecutors said. They met and were photographed at the global rollout ceremony in China for the overseas police stations.

Ms. Liu, prosecutors said, had directed “every detail” of the Manhattan station, down to the type size, logo and spacing of a banner inside the station. She wanted Mr. Lu to track down an outspoken critic of Beijing who was living in California and had taken part in the 1989 Tiananmen Square protests.

“Just help me verify if this person exists,” Ms. Liu wrote, referring to the dissident.

On the second day of the trial, two F.B.I. agents dramatically unfurled the banner in front of jurors. It read “Fuzhou Police Overseas Service Station, New York, U.S.A.”

Prosecutors said Mr. Lu had aided the Chinese authorities beyond his work setting up the station. In 2018, he sent photos to another Chinese official of two members of Falun Gong, a spiritual movement that is banned in China.

Just as the F.B.I. searched the organization’s headquarters in 2022, prosecutors said, he deleted messages from the social messaging app WeChat from his phone, which amounted to obstructing justice.

Ms. Rangel said the station was “stopped early in its tracks.” Though Mr. Lu was not financially compensated for his work, he received “continued bona fides from the Chinese government,” said Carrie Crossmore, an F.B.I. agent who interviewed Mr. Lu.

But supporters of Mr. Lu said they thought he was being punished for work that was ultimately benign.

“Harry’s motives were pure,” Mr. Carman said outside the courthouse, standing alongside Mr. Lu. “His support was there because he’s helped a lot of people in his 45 years in America.”

Baimadajie Angwang, a former New York City police officer who was cleared of accusations that he had spied for China, sat with Mr. Lu’s legal team throughout the trial. Like Mr. Lu, Mr. Angwang said he was wearing an American flag pin on his suit to quell any notion that he was disloyal to America.

“We have to do things like this to prevent people from coming after us,” said Mr. Angwang, who also served in the U.S. Marine Corps.

Michael Forsythe contributed reporting.