Two questions that nag me.

[Gordon Gray]

IMO, the slowing of the limo is very likely the result of a reaction by Mr Greer to the "Dark Compected Man" stepping into the street with a "hold it" fist in the air, just as "The Umbrella Man" was pumping the open umbrella up and down. Added to to the hard limo turn from Houston to Elm, the speed was already reduced and this occurred just as the limo should have been increasing speed.
As for the shooter of JD Tippet, I would think a description similar to the person known as Lee Harvey Oswald would somewhat match a number of individuals, especially considering the event being witnessed.

A benign explanation of Greer's behavior would be that sensing shots from the front and instinctively not wanting to drive into a hail of bullets, he hesitated, turned to look at the President, taking his foot off the gas inadvertently, saw Hill coming toward the limo, turned braked, looked back to see if Hill had made it, then seeing the President shot in the head he accelerated. Just what Kellerman was doing all this time is another story. The more sinister explanation is that Greer at least, was in on it and was reacting to the DSM's signal. But was Kellerman in on it too? Were any of the rest of the detail? The cover story seems to be that the White House wanted a lower profile in Dallas and for the President to appear open and available to the people, so the SS, bowing to political pressure pulled back JFK's protection. The agents themselves seem to believe that the President himself never interfered with their work .and they all said he was a nice man. Of course Bolden says they were a bunch of red neck racist drunks, who hated Kennedy and were lax in their jobs. I tend to believe Bolden. As for the Tippet shooting; I have a hard time believing that the plotters would go the extent of shooting a policeman in order to frame Oswald as a cop killer, in the hopes the police would shoot him. It seems much too circuitous and chancy. It was imperative that they eliminate Oswald as quickly as possible IMO, and they would have taken more direct means. I have always thought that the man walking west on 10th was the same guy who got into the Rambler. He was driven to Ruby's and told to go towards Beckley and try and intercept Oswald, who was to have been eliminated in the TSBD, but managed to get away. Oswald was headed towards the Texas Theatre to meet a contact. He must have been driven there in order to be seen there by the concessions guy at around 1:10 PM. Tippet's behavior was awfully strange that day. It could be that Tippet was also looking to pick up Qswald, take him some place where he could be done away with, and mistook the Rambler man for him. Or not. Tippet could have just been stopping him because he matched the description on the BOLO. Rambler man had to shoot him to avoid being taken, and left Oswald's wallet as further incriminating evidence. He was most likely the guy who d been leaving the trail of evidence the months prior. He then went to the Texas Theatre to shoot Oswald, IMO.