If I'm not mistaken, Mr. Snell (actually I think it's "Schnell") was also a fairly high-ranking member of the 9/11 Commission staff. I'll try to find a link for that; I'm certain that I've seen it cited here on FR.
Author/reporter Peter Lance on Snell:
As soon as I heard Snells name I suspected that what my source had been telling me was true: that the Commission staff was limiting the scope of the investigation and cherry picking evidence.
Snell had been the Assistant U.S. attorney who co-prosecuted Ramzi Yousef for the Bojinka case in 1996. In my first book 1000 Years For Revenge I recounted how the Justice Department, during Snells tenure, had limited the scope of the Bojinka case.
http://www.readersread.com/features/peterlance.htm
According to the 9/11 Commission Report Dietrich L. Snell was a Senior Counsel & Team Leader.
Yes he was staff.