ATD isn't open yet, I have some observations:
About photo #4 close-up on nail gun - evidence marker #2 - Wyatt Incident report
Some things to take a closer look at:
The floor looks very dusty. There are some white specs that look like dry-wall or plaster debris in the lower left of the photo. Was there very recent construction or repair to the room?
How does the ceiling directly above the location of the nail gun appear?
Is there any dust or debris on top of the furniture (file cabinets?) near the nail gun?
It looks like there is a hole in the floor near the nail gun. Is this a fresh mark? Is it drilled? It has a piece of debris near it, looks pink. Perhaps a bit of paper.
It looks like there is a footprint between the nail gun and the area of the (what looks like) hole.
It looks like there are fresh scuff marks in the floor just above the rear of the nail gun, as if the nail gun had been stepped on and it slid along the floor.