A marble statue of a reclining half-clad female is carved in the lid of the funeral box.
U.S. Immigration and Customs Enforcement agents said Friday the statue appeared at a public exhibition in New York as recently as last week. Authorities don't know when it entered the U.S.
Federal prosecutors said in court papers filed Thursday the statue is believed to be one of the antiquities illegally obtained by Italian art dealer Gianfranco Becchina.
Becchina was convicted in 2011 of trafficking in plundered Roman artifacts. He ran an antiquities gallery in Basel, Switzerland.