Authorities have seized an ancient Roman bust that a Massachusetts museum owned for nearly six decades, after evidence emerged that the piece had been looted, one of several instances in recent years of cultural institutions turning over objects because of ethical concerns and part of a wider crackdown on stolen artifacts.

The Worcester Art Museum, about an hour from Boston, said in a statement last week that it had "transferred ownership" of the 2nd-century bust "Portrait of a Lady (A Daughter of Marcus Aurelius?)" to the New York County district attorney's office so it could be repatriated. A June search warrant from the New York County Supreme Court ordered the museum to hand over the bust.

"Based on the new evidence" from investigators, "the Museum determined that the bronze was likely stolen and improperly imported," the statement said.

"With its limited resources, the Museum has not been able to prioritize provenance research of its existing collection," the museum said in an emailed statement, adding that it will be hiring a provenance research specialist and "increasing its scrutiny of its existing collection."

Experts believe the bust, created between A.D. 160 and 180, came from a large imperial family shrine in Turkey and depicts the daughter of an emperor - possibly Marcus Aurelius or Septimius Severus. The museum's wall text described the work as a "rare, life-size portrait," and it is valued at $5 million, court documents say.

The transfer is one of the latest developments in an ongoing investigation by the Manhattan district attorney's office into a smuggling network involving antiquities looted from Bubon in Turkey and trafficked through New York.

The district attorney's office is known for its Antiquities Trafficking Unit, which according to a July release has repatriated more than 950 antiquities stolen from 19 countries since early 2022.

The investigation has turned up treasures across the eastern United States. The Cleveland Museum of Art recently had a $20 million headless statue of Marcus Aurelius taken by authorities, while the Metropolitan Museum of Art saw two bronzes - depicting Septimius Severus and Caracalla and valued at more than $26 million in total - seized this year, according to search warrants. Artifacts were also removed this year from Christie's and Fordham University, according to the warrants.

Museums have come under heightened scrutiny in recent years amid a global reckoning over how collections are acquired. The movement has rattled institutions large and small and exposed the reality that many prized objects displayed in prominent museums carry dark histories of exploitation and theft.

The artifacts in the Bubon investigation will join a long list of objects removed from museums and returned home because of either court orders or nagging consciences - including several Benin Bronzes, the Gilgamesh Dream Tablet, the Easter Island Moai statue and more. (The British Museum continues to hold onto its Benin Bronzes and the Elgin marbles despite wide criticism.)

Alexandra Sofroniew, a professor who studies ancient Greek, Roman and Etruscan art at the University of California at Davis, said in an email that she is "heartened to see museums responding swiftly, sincerely and positively to repatriation requests," but there is "still a lot of work to do in terms of returning objects to their places and peoples of origin."

The Worcester bust, which stands about 21 inches tall, is notable for its large scale, Sofroniew said, noting that "it is relatively rare for bronze statues to survive from the ancient Mediterranean world," as they were often melted down and reused in later years.

According to Sofroniew, the bust probably stood in what's known as a sacellum, akin to a family chapel.

Women in ancient Rome had more freedoms than in other classical societies, and the bust reflects "how the portrait and persona of a young Imperial woman could act as an inspiration, comfort or authority," she wrote, likening the woman to "an ancient influencer."

When the Worcester Art Museum bought the bust in 1966, the vendor said it had been found in the Roman province of Lycia, present-day Turkey, the statement from the museum said. But investigators provided new information early this year, "prompting the museum to cooperate with the DA's investigation of the object's history of ownership."

On a now-removed webpage, the museum listed controversial collector Robert E. Hecht Jr. in the work's provenance. Hecht, who died in 2012, was known for his dubious collecting practices, particularly after he revealed that he had misled the Metropolitan Museum of Art about the provenance of a Greek vase. Valued at $1 million, the piece had come from local suppliers who dredged it up from ancient tombs and smuggled it out of Italy.

A Washington Post obituary described Hecht as a "legendary but mysterious figure" whose "passion for ancient art overcame any questions about the destruction wrought by its illicit origins."

Worcester Art Museum director Matthias Waschek said in a statement that the museum was "thankful for the new information" about the bust and is "committed to managing its collection consistent with modern ethical standards."

"The ethical standards applicable to museums are much changed since the 1960s," he said.