If you listen very carefully to the tapes, you can just make out the sound of a second DT gagging behind the grassy knoll.
Don't know enough about Dean to know if the hunch is sound, but I can't see it being either Haig or Kissinger - what was in it for either of them?
We have a very different politico-journalistic culture in Ireland. A commentator (I think it was John O'Donoghue who became a lecturer in journalism) quipped shortly afterwards: "If Watergate had happened in Ireland, everyone would have known who Deep Throat was, but Nixon wouldn't have had to resign."