Exactly what I think! ^^^ some graphic info below.
I’ve been to southern AZ many times, and the desert is vast, with lots of tumbleweed, short shrubs, cacti, some tall8 ft, mostly around 4-5 ft tall. Very unforgivable land. I would think, it would be very easy to hide a body. The dryness and hot sun, shrinks the DB( sorry), to just bones in less than a month. Unrecognizable, maybe even DNA gone, not sure.
Since this is also an immigrant route, many passing die going through the hot desert. They say there are many bones( sorry, graphic). I think it’s already been in the 80s+ in AZ and it’s just Feb.
All just my opinion.