I've been tending to ascribe to the "vestibule attack" theory as well--only because 1) her attack wasn't caught on camera, and 2) the vestibule is (technically) inside the church and in the SW corner if the church. When she is described as "walking down the hall" to the vicinity of where the suspect was, I envision her unlocking and entering by way of main entrance door (middle of church), then turning right and proceeding down the hallway to the porte cochere entrance where she'd parked--to open those doors from the inside in order to bring in her unloaded camp equipment. Not that that envisioned scenario is necessarily right...it's just the way my own mind has put it together based on pressers and media statements. LE also told us she was "ambushed" - and I've envisioned SP hiding in the darkened vestibule, maybe behind something like I see in there behind the propped open door in the video. If he DIDN'T hide in the darkened vestibule area, he'd have been seen by Missy long before she reached him because the motion-activated hall lights would've turned on as she walked down the hall.
Anyway, regardless of how she entered...if the
exterior SW doors aren't broken (and I can't really tell from the crime tape photo above if ALL them are intact or not) then maybe the
inner set of vestibule doors - maybe the one propped open - had some breakage during the attack?
Just a guess, of course. But I don't see how the broken glass seen near her body could be from a glass hallway table being broken. If she'd died near that hall table, her attack would've been recorded by the motion-activated hall cameras. (But we're told it was not.)
ETA:
Just to be clear (I hope)...
. The vestibule (at least how I'm describing it!) is the area between the inner and outer sets of glass doors. The outer doors are in your photo above with yellow crime tape across them. The inner glass doors are, for example, the one propped open in the video as swatperp walks by. There is usually a mat on the floor of the vestibule between outer and inner sets of doors for tracking rain and dirt in on before entering the building proper.