I don’t have time to read through all the posts, so I apologize if this has already been noted. Looking at the straps in the backpack, and how they reflect in low light, it appears to me that these might be the reflective straps of a Timbuk2 backpack:
https://cdn.accentuate.io/1470283448362/1662060336076/timbuk2-parker-commuter-backpack-jet-black-1387-3-6114-3A-SML_3.mp4?v=1662060336076
Timbuk2 does not have a store in Arizona, but they do sell out of REI, and there is a REI in Tucson near the Catalina Foothills.
Just a thought.
good find