The West elevator in the TSBD was the one which had a push button and could be returned to the floor it left from by closing the gates. It would apparently automatically return to the floor according the BR Williams WC testimony:
Mr. BALL. Which elevator did you take?
Mr. WILLIAMS. I took the east elevator down.
Mr. BALL. Is that the one that is worked with a hand--
Mr. WILLIAMS. Yes, sir. That is the one with the one gate, and works with the hand pedal.
Mr. BALL. How does the other one work?
Mr. WILLIAMS. The other one worked by push button. You have two gates to pull. That is the one you can pull two gates on and it will come back up by itself. The east side elevator won't come up unless someone is operating.
This leads me to a speculative alternate theory of how a gunman at the Southwest corner window could have escaped after firing the Z313 kill shot, gotten down and out of TSBD unseen, and the gun he used also not found.
Here is the sequence:
1. SW window 6th floor gunman runs along the open west aisle of the 6th floor, toward the West elevator, (100ft away) and at one of the windows on the WEST side of the building drops his rifle out that window, where it falls to the rooftop of the loading dock annex building, The shooter then reaches the West elevator approx. 12 sec posts shots, and takes the West elevator to the 1st floor, exits it by 45 sec post shots, then escapes out the TSBD by West side open rollup door by 55 sec post shots.
2. An accomplice on the roof, picks up the rifle as soon as it landed, at about 7 sec post shots, runs across the roof, over rear side and drops rifle to car trunk which is closed by the driver and the driver then drives car away from TSBD with the rifle as early as 20 sec posts shots. The accomplice climbs down from the annex roof by 20 sec post shots, walks away from the TSBD.
How is the West elevator used, 1st by the 6th floor SW window shooter, and then by Jack Dougherty, yet the elevator is not seen by Victoria Adams nor Sandra Styles starting down 4th floor staircase by 30 sec posts shot, nor seen by Dorothy Garner exiting the 4th floor office approx. 35 sec post shots?
Solution:
If the 6th floor SW window gunman begins moving West elevator at 12 sec post shots from 6th floor, and can travel 1 floor every 5 secs, the elevator would be completely past the 4th floor landing by 27 secs post shots, and would reach the 1st floor easily by 45 sec post shots.
IF the gates of the West elevator were closed by the gunman at 45 sec post shots, then the West elevator auto returns itself to the 6th floor by 70 sec post shots. There it would be seen on by Truly looking up the elevator shaft when he and Baker reached the 1st floor elevator approximately 70 sec post shots. (Baker/Truly must have taken at least 70 sec to reach 1st floor elevator shaft, otherwise would have had LOS to Adams/Styles coming down last leg of 1s floor stair as B/T approached diagonally across the 1st floor.)
Baker/Truly take 5 secs to walk from east side 1st floor elevator, 10 secs to ascend 18 step staircase, 5 sec for Baker to walk over to 2nd flour lunchroom and thru the 2 doors, and then approx a 15 sec interval with Oswald in the lunchroom. So at least 30 seconds of time which is enough time for Jack Dougherty to have taken the West elevator down from 5th floor to the 1st floor after Truly had looked up the shaft at 70 sec post shots. The West elevator would have passed by the 2nd floor landing while Baker is IN the 2nd floor lunchroom and Truly is leaning in thru the outer door. Thus neither Truly nor Baker had LOS to West elevator shaft at the time of the elevator passing the 2nd floor landing with JD on it, and both B/T being distracted and focused on Oswald.