The dress was part of a public exhibition of Callas memorabilia marking the 30th anniversary of her death.
The theft occurred last Friday, May 25. Police believe that the culprit may have removed the dress, valued at €100,000, on behalf of a collector. According to the newspaper Kathimerini, institute director Melita Palestini said that the location of the dress, in a corner behind a column, might have made it easier for the thief to steal it.
Callas was born of Greek parents in the U.S. and became a Greek citizen at 43 in 1966, at the end of her relationship with Greek shipping magnate Aristotle Onassis. She died 11 years later in Paris.