The Houston bronze krater

The bronze krater (once) on loan to Houston is mentioned by Monica S. Dugot, Thomas R. Kline, Jennifer Anglim Kreder, and Lucille A. Roussin, "Legal and Ethical Problems in Art Restitution", in a paper given in New York on April 4, 2008.

... a bronze krater is currently on loan to the Museum of Fine Arts in Houston from the Shelby White –Leon Levy collection, and there are calls for the museum to release its provenience history. 

As far as I know the collecting history for this krater has not been released.

Interestingly the cases relating to cultural property in Minneapolis (2011) and Toledo (2012) and mentioned in the same paragraph have now both been resolved.