PIM, Came up with this earlier which was relayed to police:
It appears that the weapon/instrument the killer was carrying in the hallway closely resembles a rock pick hammer used by mountain climbers. They might want to check Lowe's (maybe they have) for recent purchases.
Also...and this is touchy, but I've not seen it come up, yet, and I think it's an important consideration...have LE considered that the killer could've been a camper in that class, who maybe arrived early, killed Missy, stashed the swat stuff in a duffle, arrived on scene (again), and then left with the other classmates? It's the only way I can fathom that bloody swat uniform leaving the premises undetected.
Sent from my iPhone