LIGGIT Segment from TMWKK 7

This is the guy some think did the post mortem cranial surgery. I don't buy it but that is their theory. However he was hired to do SOMETHING. Horne thought the tracheotomy might have been done on the plane but I don't know if he still does.
Where was the post-mortem surgery (to remove not only the bullets but the entire brain/what was left of it) done: there, at Walter Reed Hospital, or in Bethesda?