Checked the Paschall lead... Cannot find a clear copy...
Indeed... This fellow shows up very likely within one minute of the kill shot...
Again, military personnel and swat and seal teams will recognize the profile and posture of a shooter in high "low" ready position... who is perhaps using his scope to "assess damage"...
This should change the conversation a bit... regardless of all the junior high put downs from a member or two...
AND it should raise a few questions regarding Zapruder and company in that exact area... before, during and after the kill shot...

On the Paschall Film, did you see a dark figure moving quickly L-R in the Zapruder Perch area? I'm not sure what you were able to see on the Paschall copy you examined.
Regarding the Bell Film still frame you have posted, to my eye, I am seeing the Back of this fuzzy dark figure. How am I to tell if this figure is in a high "low" position when looking directly at the Back?