Photos and films documenting the event could show Secret Service participation in JFK’s murder. A thorough cover-up is necessary as a matter of personal/institutional survival not just “embarrassment”.
Have scores of phony credentialed persons in Dealey Plaza to collect ALL photographic stills/movies. Alter photographic evidences before returning to their rightful owners. What cannot be altered is conveniently “lost” like the “Babushka lady”’s movie film. Create climate of fear by killing key witnesses. Photo alter films so eyewitnesses cannot be found; example do these spectators look like what we see in the Zapruder Film? Who are they? Have they come forward or are they scared they will be murdered by the U.S. Government (the conspirators)?