Regardless of how and when the 19th dynasty mummy mask now in the St Louis Art Museum (SLAM) actually left Egypt, the fact is that it was discovered on a state-funded excavation in 1952 and is documented as having gone from there to the Sakkara storerooms. Mr Benjamin claims that the Egyptian Authorities can provide "no documentation" that "it is stolen" - but they can provide documentation precisely how it came to be where they say it should be. So if we are quibbling about quality of documentation, can the US museum provide documentation showing how precisely it left that excavation and arrived in their galleries? Well, no, in fact it cannot. All it can provide now is a little unverifiable hearsay obtained from the Aboutaam brothers from whom they bought it (at least some of which now turns out to have surfaced only after the purchase).
We are not talking here about something from some unknown farmers' clandestine grave robbing brought back from a rich banker's Nile cruise in the 1880s, but an artefact documented (as even SLAM admits) as having come from a state-funded excavation a few decades ago. It was recovered not by some foreign expedition working in Egypt, but an Egyptian one. This artefact incontrovertably belongs to the Egyptian people, who of course saw none of the cool half a million that this object is reputed to have cost St Louis.
Once these facts became clear in 2006 (when Mr Benjamin was already in the post), the question should not have been "whether" SLAM should return it, but how best to resolve this. SLAM's foot dragging really does the image of US museums (and thus the US itself) no favours.
From the comments I have seen in the web recently, I wonder how well public opinion in North America is informed about the background of this case. Some of the dealers and collectors on US-based discussion lists are coming out with some rather ignorant and misguided statements in response to Cremers well-founded anger. It was Cremers who first started the ball rolling back in 2006 and brought attention to this issue.
Photo G.W.Bush (Facebook) and the 19th dynasty mask in the excavated grave during Sekhemkhet pyramid excavations at Sakkara (from M. Zakaria Goneim's 1957 "The Buried Pyramid", London).