A tug of war has broken out over an ancient relic from Lebanon that New York’s leading art museum suspects may have been stolen during the Lebanese civil war.

Manhattan prosecutors have impounded the bull’s head and are seeking to return it to Lebanon. But husband-and-wife art collectors from Colorado have filed their own lawsuit, seeking the relic be returned to them.

Believed to be of Greek origin, the marble head dates back to around 360 BC and is 13 inches (33 centimeters) tall.

It is the second item from the Metropolitan Museum of Art to wind up in the hands of prosecutors in recent weeks. In late July, the Met also surrendered an ancient vase amid concerns that it might have been stolen from Italy.

Lynda and William Beierwaltes initially purchased the head in 1996 from a London dealer, who had bought it from an art dealer in Switzerland. According to The New York Times, they paid $1 million for the artwork.

But in 2010, the couple sold the head to a private collector in the United States, who loaned it to the Met, which put it on public display.

After a curator discovered it may have been stolen from government storage during Lebanon’s civil war, the Museum said it took “immediate action” and handed over the head to the Manhattan district attorney’s office.

“We contacted the Lebanese government and the lender, we took the item off display, and we have been working with federal and state authorities,” said Museum spokesman Kenneth Weine.

But when Lebanon demanded restitution, the Beierwaltes, who rescinded the 2010 sale, filed a 20-page lawsuit in a US federal court against Lebanon’s directorate of antiquities and the New York district attorney’s office.

“The Beierwaltes are bona fide purchasers with clean hands. By contrast, for more than 50 years, Lebanon has failed take any action domestically or internationally to report any theft of the bull’s head,” said their lawyer William Pearlstein.

Pearlstein says there were no grounds under federal law for state prosecutors to seize the relic and that even if the head had been stolen, the statue of limitations under Lebanese law has expired.

The district attorney’s office declined to comment.