It's the difference between targeted murder = death penalty; while interrupted nervous burglar commits murder during other felony could = Life or LWOP. If this is targeted, SP cannot know for a fact how it will go down, so he doesn't want the murder itself on film. Also the forensic podiatrist remarked that MB fought hard, so it may be that SP's gun was a last resort when bludgeoning with tools wasn't working, i.e. faux burglary gone bad.
Thanks! That is a very important clarification that there were no cameras at the NW and SE.
No camera in the SE corner, but I would bet there is broken glass or some other little things like beads, pieces of plastic, some clutter on the floor back there, too. I do not believe SP was meandering around. I do believe everything SP did was purposeful.
Remember the first movie Mission Impossible with Tom Cruise. He goes to the safe house apartment where he uses his handkerchief to unscrew a hot lightbulb in the hallway outside the door. Then he steps on it, and uses the hanky to scatter the broken glass on the landing. Why? Two reasons: dimmer light, and so anyone approaching will make crunching noises on the glass that Cruise will hear.
IMO As shown on your floor plan and seen on film, SP left broken glass in multiple places. This is just what we know about, there could be more, e.g., you have now disclosed about the broken glass display case in the far NW main hallway which was unknown when you made the floorplan. So there are several critical positions of known broken glass left on the hard floors by SP. I don't think it is mere vandalism. IMO SP has two purposes: to hear approaching or running away feet crunching on the glass, and if it is a targeted murder and MB happens to run in any hallway and to most exits, she might slip and fall on the glass. I wonder if MB was chased or did slip or fall on broken glass or baubles.
This makes sense for why SP exits room 10 to break glass on door 9 as shown on camera - to scatter glass on the floor there. Why? Because room 10 has at least two doors and room 9 connects to the auditorium, and this point in the back hallway is near the intersection to the kitchen hallway and NE exit, places for MB to run away and to hide. I have mentioned before that IMO SP is not checking every door for locked or open, then entering the unlocked looking for items to steal, but rather SP is searching for room-to-room connecting inside doors either for MB to escape or for SP to escape, or to hide. SP was prepared for hunting down MB if the first strike failed.
IMO everything is pointing increasingly to MB was targeted. Your opinion that MB was attacked in the NW corner makes sense because then she was lured far away from her truck. MB felt very safe leaving her purse, keys, phone, loaded gun and the truck itself behind. SP may have called her by name, or called out for "Help! I need help!". Whatever MB seemed to hear as reported by the forensic podiatrist, IMO it was not frightening or she would have retreated to the truck. MB was not an LEO or military with public responsibility, nor was she a man trying to be a hero. She was a mom, wife, teacher and fitness instructor, with no LEO training, and a small woman, so like most women, she would not move forward toward perceived danger to herself.
All JMO and some thoughts