All this talk about technologies that “should have been used“ to check for finger prints… if the prints are from someone who lives at or commonly visits or uses the area, the prints would likely be useless UNLESS they are made after the blood or brains hit the surface on which the print appears. And the person who lives there and was at the scene had already admitted touching the victims and one victim’s phone, so had a plausible excuse for why his prints might be there.
And, at this remote, rural site, how likely is it that anyone other than family or someone who commonly visits the site is the killer who just happened to kill there when PM and MM were visiting? Very few people would know they were going to be there.
A remote, outdoor site, in darkness, in the rain… with a scene that should be secured because the identity and location of the killer and weapons are unknown… certainly some choices must be made early. While I agree that cover from the rain should have been placed ASAP (and as I recall, was ordered by the sheriff) and strong lighting should have been placed to assist with early investigation as well, all this second guessing and suggested application of standards is excessive.
And none of it addresses the fact that Alex lived there, was the last with the victims moments before their lives ended, had motive to eliminate them, and that he lied about that fact.