Last month, Dallas-based Heritage Auctions and the president of Mongolia announced they were launching a joint investigation into how Heritage wound up nearly auctioning off a near-complete Tyrannosaurus skeleton — before the sale was dramatically interrupted by legal concerns over whether the museum-quality, million-and-a-half dollar bones had been looted/smuggled.

Today, “Pheet Bharara, the US Attorney for the Southern District of New York, in a joint investigation with the Immigration and Customs Enforcement, a division of the Department of Homeland Security, announced that they had filed a civil complaint in Manhattan Federal Court seeking seizure and forfeiture of the skeleton so it can be returned to Mongolia,” reports the New York Observer.

The reasons this is a New York matter: The auction was in New York and the bones currently sit in crates at Cadogan Tate, an art storage facility in Sunnyside, Queens. The auction was interrupted by Robert Painter, a lawyer for Elbegdorj Tsakhia, the president of Mongolia. For several weeks earlier, paleontologists had been publicly questioning the skeleton’s provenance and the legality of the sale, but Heritage went ahead with it. After Painter’s interruption, security guards and Greg Rohan, Heritage’s president, talked it over with the lawyer in a corner of the room.

The next day, Painter filed a lawsuit against Heritage Auctions in Dallas, alleging the skeleton was taken from Mongolia. Under Mongolian law, “the export of dinosaur bones and fossils is a criminal offense.” The Observer reports the federal complaint also indicates:

Importation documents from March of 2010 (when the consignor of the bones brought them to the states) incorrectly described the contents of the boxes containing the skeleton (a sampling: “…broken fossil bones, three rough fossil reptiles, one fossil lizard…”) and underreported their value (listing it at $15,000, when it was listed in an auction catalog at a starting price of $950,000 and ended up selling for $1,052,500)….

Jim Halperin, co-chair and co-founder of Heritage Auctions, told The Observer through a spokesman, “We haven’t seen the lawsuit yet so it would be inappropriate to comment.”