A three-judge panel in Athens ruled that the statute of limitations had expired for the alleged crime, the Los Angeles Times reported Tuesday.
"Whereas the decision today was based on the statue of limitations, at no stage of these proceedings was any proof of a crime presented by Greek prosecutors," said Harry Stang, True's U.S. attorney.
True, the former curator for the J. Paul Getty Museum in Los Angeles, was not present for the hearing.
She had been cited for her role in the purchase of an illegally excavated golden funerary wreath, which the Getty reportedly bought in 1993 on her recommendation.
During the last year, the Getty has returned the wreath and three other antiquities to Greece and agreed to send 40 ancient objects back to Italy, the Times said.
True remains on trial in Rome for allegedly trafficking in antiquities looted from Italy.