See post 12. The Phoenix PD has a PC-12 outfitted with cameras. It looks like the pattern center is almost directly west of the Fairgrounds/Stadium and the east/west sides of the pattern are about 2/5 miles west of the stadium.
How do you know its not some realtor shooting buildings for sale or a contractor/architect looking to make upgrades or new buildings? If it is police, they are not even close to the center where the count is going on, and are doing some other investigation?
I wouldn’t doubt if there are a number of entities both gov and civil that have those types of planes in that area; pointing to one or the other is useless speculation unless you get a tail number.