I think a close analysis of this Altgens photo would show alterations... and verify a third person who has been blended into the backs of Z. and S....
It Has all been studied before, Jake. I have discovered more shooters than you could find holes in a Tramp's vest.
All have been self debunked by myself on a public Forum many years ago.
The Tripod was first speculated by myself in the year 2002, and is written about in the 2003 Book "The Great Zapruder Hoax"
As indicated above, after more study I later debunked my own stupid theory simply by applying common sense, logic and reason.
Jim Fetzer ( AKA The Nutty Profetzer ) fell out with me because I asked him not to publish my mistaken and idiotic theory, but Fetzer being Fetzer, knowing it was nonsense, went ahead and published the photo analysis in his wacky book anyway.
Regarding the Altrgens photo, the late Bernice Moore was the first person point out a potential third man. I colorised her observation for her.
And here is Zapruder heading back to Jennifer Juniors with the Camera case seen in this later image.