Mr Graves;
Remembering that the DallasCountySheriff's Office Building being located on Main St at Houston St, places it just across the street from DealeyPlaza, and with DCS Deputies standing on the corner of Main at Houston allowed for quick area access for them to the scene.
I believe that MarilynSitzmanImage is pictured being interviewed by DCS Deputy John"Bill"WisemanImage.
And, I believe that StellaJacob, GloriaHolt, and SharronSimmons had been, or were, interviewed by DCS Deputy CL"Lummie"Lewis soon after the shootings of JFK Sr and JBC Jr.
http://mcadams.posc.mu.edu/russ/testimony/lewis_cl.htm
Mmmm. Specifically what attracted mass numbers of law enforcement standing on the corner of Houston/Main to the railroad car area well behind Zapruder/The Pergola? How does this same area somehow become "The Scene" as you call it?
Regarding Darnell, it took him an extended amount of time to progress down Elm St . The recently discovered Darnell film snippet shows both Press Buses on Houston St well Behind Darnell. From the (S) side of Elm St, Darnell allegedly filmed the lead Press Buss going under the Triple Underpass. We know this portion of the JFK Motorcade came to an absolute Dead Stop immediately following the Kill Shot. How is it the Lead Press Bus after sitting at a Dead Stop somehow managed to PASS Darnell on Elm St? Darnell on foot & unimpeded progressed down Elm St at an extremely slow pace. Darnell's "snails pace" needs to be considered when time stamping the alleged footage he captured of the railroad car/Pergola area.