There are some more documents that I need to add that relate to the OP and will do so when I get some time to do so.
However I would like to make the following observation. The vast majority who responded in the thread thought it likely, that given the circumstances, Norman and Jarman would lie to help Williams. We have early reports that a coloured man was reported as being involved in the shooting. Also it was widely broadcast that the assassin had lunch while waiting for the President. Without the corroborating evidence provided by the Dillard photo.......how good an alibi would it be for Norman and Jarman just saying Williams was with them at the time?
Up until Oswald's death Williams had only this for corroboration provided by Jarman's initial affidavit
"At about 11:45 a.m. all of the employees who were working on the 6th floor came downstairs and we were all out on the street at about 12:00 o'clock noon. These employees were: Bill Shelley, Charles Givens, Billy Lovelady, Bonnie Ray (last name not known) and a Spanish boy (his name I cannot remember). To my knowledge Lee Oswald was not with us while we were watching the parade."
Also Willliams had changed his original story from going up with the others on the west elevator and after a few minutes the parade arrived to going to the 6th floor by himself and joining the others almost half an hour before the motorcade by the next day.