In April 2010 Zahi Hawass "turned over to the U.S. Department of Homeland Security 'all the evidence that I have to prove that this mask was stolen, and we have to bring it back'." [full story]
It now appears that the St Louis Art Museum (SLAM) is so worried about the issue that it has taken out "a civil action for declaratory relief concerning the ownership and possession of an Egyptian mummy mask known as the Mask of Ka-Nefer-Nefer ("Mask"), an approximately 3,200 year old Egyptian cartonnage mummy/funerary mask, which was discovered in 1952, purchased by the Museum in 1998 and remains owned and possessed by the Museum." [full statement]
The "factual allegations" note that the mask was excavated at Saqqara.
In or about 1952, the Mask of Ka-Nefer-Nefer was discovered during an excavation of the unfinished Step Pyramid of the Third Dynasty ruler Sekhemkhet on the Saqqara necropolis. The excavator was Mohammed Zakaria Goneim (“Goneim”).What is more interesting is that it is claimed that
In the early 1960s, the Mask was a part of the Kaloterna (or Kaliterna) private collection, during which time it was purchased by Ms. Zuzi Jelinek (“Jelinek”), a Croatian collector in Switzerland. In or around 1995, Jelinek sold the Mask to Phoenix Ancient Art, S.A. of Geneva ("Phoenix"). On or about April 3, 1998, the Museum purchased the Mask from Phoenix.It is interesting to observe that the "factual allegation" is unable to be sure about the correct name of the Kaloterna / Kaliterna collection. The fact is that Ms Jelinek appears to have "sold" the mask to Phoenix Ancient Art, S.A. in 1995. For the next two years it appears to have resided in North America.
It would be interesting to see the full set of authenticated documents for the period covering the period from 1952 to 1995.
The case is discussed in Laura E. Young's thesis that includes fascimiles of the relevant letters. [discussed here]
It would be inappropriate to speculate on why SLAM has chosen this moment to serve the legal papers.