The identification of Ka Nefer Nefer

I have already reflected on the significance of 1999 for the collecting history of the Ka Nefer Nefer mask acquired by the St Louis Art Museum.

It now appears that a member of the curatorial team at SLAM was informed about the Saqqara link by an Egyptologist at a major encyclopedic museum less than a year after its acquisition.

This is correspondence that has not been mentioned in the discussion of the mask up to this point.

During the subsequent few months Sidney Goldstein seems to have been made aware of Charly Mathez's claim to have seen the mask in Belgium, and in late September 1999 Goldstein wrote to him for clarification. (Up to now it has not been clear what prompted Goldstein to write his letter.)

Did Goldstein write again to Mohammed Saleh in Cairo seeking further advice? Which Egyptian officials were contacted by SLAM curators in 1999 to check out the Saqqara story?

What additional due diligence steps did SLAM undertake to explore the emerging collecting history for the mask?