As usual, your keen eye has uncovered that which has been in plain sight. Do you know the Time Stamp of this 3 Tramps photo? Based on his angled in-the-air (R) foot, he is turning the corner as the 3 Tramps in front of him just did. Is this guy trailing the 3 Tramps immediately after the Dallas Police Dept interfered with a train yard rendezvous?
Billy Bass, below
He stated (1977) during an interview for HSCA hearings that after walking the tramps to the county jail he went back to the TSDB and shortly after he first heard about the Tippit shooting (1:18pm). Annoyingly, in all the interviews I've looked through with cops involved in the movements of the three tramps weren't asked what time these events took place. It might have been the first report of the Tippet shooting Bass heard, that day, doesn't mean it was the 1:18pm time.
From Denis Morrissette's website.
I think Jim Garrison investigated the approx time - using shadows and it came to between 1pm and 2pm.
I've looked at all the other tramps photos and there's no other sighting of the DCM looking fella.
I imagine he was lurking somewhere off to the side as they were marched along the south west wall past the ring fencing. There must be so many more photographs were not seeing.