But does any of this prevent Oswald getting to the 6th, assembling the MC, taking up his position,and killing JFK..no. Rowlands claim that he saw a man with a high powered rifle in the west end og the 6th floor, at about 12.15.If that is true it follows that Williams goes down to the 5th before 12.15. Which in turn means Jarman & Norman are back on the 5th much earlier than the 12.25-12.28 timeslot.
The accuracy of these witnesses times or locations cannot be completely guaranteed. And no concoction or interpretation of their various comings and goings during the 11.45-12.30 timeslot can be pointed to to make any real claim that prevented a determined and cunning person from being on the 6th floor to carry out an assassination.
I believe that determined and cunning person was Oswald.Nothing in this thread disproves that possibility.