Forensic archeologist Christos Tsirogiannis is no stranger to this blog. He's helped identify and return quite a number of ancient artifact from the collections of museums, galleries and even private owners now. The New York Metropolitan Museum of Art delivered an ancient vase to Manhattan’s district attorney, after the DA had issued a warrant for the Greco-Roman vessel on July 24, citing “reasonable cause to believe” the museum was in possession of stolen property. That cause was Tsirogiannis' evidence.

For decades it was proudly displayed in the Greco-Roman galleries of the Metropolitan Museum of Art, a 2,300-year-old, vividly painted vase that depicts Dionysos riding in a cart pulled by a satyr. It was seized last week based on evidence that it had been looted by tomb raiders in Italy in the 1970s. The museum staff hand-delivered the object to prosecutors and anticipates that the krater will ultimately return to Italy. Kenneth Weine, a museum spokesman, said in a statement:

“The museum has worked diligently to ensure a just resolution of this matter.”

Questions about the vase’s provenance surfaced in 2014, when The Journal of Art Crime published an article by Tsirogiannis, in which he offered evidence the vase had no collecting history prior to 1989, and it matched photos in possession of  Giacomo Medici, a 79-year-old Italian art dealer who was arrested in 1997 and convicted in 2004 of conspiracy to traffic in antiquities. Tsirogiannis wrote that the item was likely illegally excavated after 1970, when UNESCO prohibited illicit trade of cultural property. He sent evidence of his discovery to the museum but never heard back.

More recently, he grew frustrated that no action appeared to have been taken. So last spring he sent his evidence to a Manhattan prosecutor, Matthew Bogdanos, who specializes in art crime. That evidence included Polaroid photos shot between 1972 and 1995 that he said were seized from Mr. Medici’s storehouses in 1995 and that showed the same Python vase still encrusted with dirt.

“When I sent American police the information, they immediately told me that this was ‘a great case.' It was abundantly clear that this rare object had been stolen.”

Mr. Medici, reached in Italy, denied any role in connection with the recently seized vase, which the Met bought at auction at Sotheby’s in 1989 for $90,000. An official for the auction house declined to identify the consignor, citing privacy concerns, but said Sotheby’s had no knowledge of any issues with its provenance when it handled the sale.

Experts date the vase, which is also known as a bell krater, to 360 B.C. and attribute it to the Hellenic artist Python, considered one of the two greatest vase painters of his day. It's a remarkably intact survivor of an age when the ancient Hellenes colonized Paestum, a Mediterranean city in the Campania region south of Rome, and created temples and artworks of legendary beauty.

The case closely echoes the removal of another terra-cotta wine vessel, the Euphronios Krater, from the museum in 2008 after evidence surfaced that it had been illegally excavated from an ancient burial ground in Italy. Met officials said they believe, as do law enforcement officials, that both vessels went through the hands of Medici.