Thanks Mr Speer.
SS and FBI both suggested Z207 as first hit. Within days of the assassination.
If you haven't looked at Chapter 2b at patspeer.com, you should probably give it a look.
Purvis and I used to hash it out on the Ed Forum. He had it in his head that the SS and FBI were on the up and up, and that the WC came along and dismantled their work.
But Purvis had NEVER bothered to read the FBI and SS memos and reports on this stuff. It turns out that the FBI and SS both claimed the head shot occurred way past Kennedy's position at Z-313, and that Eisenberg and Specter caught them in this charade, and tried to straighten things out, so that their single-assassin solution wouldn't collapse under even the slightest analysis. This is all demonstrated on my website.
In essence, I believe the SS and FBI were concerned the shots were fired too closely together, and that they deliberately moved the head shot (which they believed was the last shot) further down the road so as to give the assassin (whom they believed to be Oswald) more time to fire the shots. They fudged their work. And got caught.
FWIW, when confronted with the FBI internal memos proving the FBI assumed the last shot was the head shot, Purvis claimed they'd all been faked by Specter et al, to cover their tracks. These were the FBI's internal memos, from the FBI's files, which had never been provided the Warren Commission.
I lost respect for Purvis at that point.
We'd been colleagues, of sorts, in that we were at one point the only two researchers pushing there was a shot after the head shot. But I couldn't go along with his claim Specter and Eisenberg and Belin et al were the bad guys in this whole fiasco, and that the SS and FBI were innocent. At the time I wondered if anti-semitism had clouded his thinking, but later came to believe his military background had led him to favor what he interpreted as hard-working men of action over sycophantic lawyer-types. And I can't say I disagree with him in that bias...