I don't know if the reason a gun was involved in the deaths of these two will be established with absolute certainty, but I suggest to you that this was premeditated murder rather than anything remotely to do with mercy.
It is true that the Maze Loop at Joshua Tree wouldn't be anyone's first choice to hike in the summer, given the intensity of the heat (which in my mind is suspicious, frankly), but let us assume that you are determined to experience the desert in one of the hottest periods of the year and head out on the loop trail anyway.
The Maze Loop Trail is not one of the most obscure trails in Joshua Tree by a long shot. The trailhead is on a paved road, and there is a small parking area there. Despite many suggestions that these two could have gotten lost on the trail because they mistook a wash for the trail, or some other farfetched theory, the fact is that this trail is used by hundreds (if not a few thousand) of people without mishap every year. High level hiking skills are not necessary to follow this loop trail that is not all that far from civilization. You simply show up with proper attire, appropriate footwear, and lots of water. And then, you walk a reasonably well marked, highly used trail that is accessible from a paved road that cars travel down with regularity. A prudent hiker would stay close to the trail which ends where it starts, or you could turn around at any time to get back to where you started.
It is no surprise that these two were found in an area that the trail would not even be close to leading to. Sure, maybe they were on drugs in 110 degree heat and just decided to wander off-trail into a untraveled, rocky, desolate canyon where they could not only get lost, but maybe also hurt themselves scrambling over some loose rocks in the process. Do you really think this is that likely (although not impossible)? Do these two fit the profile of devil-may-care (or experienced) off-trail hikers that love straying from a well-beaten path?
The relationship between these two is ill-defined, except that they were no longer dating, but were now "friends" that wanted to hike in conditions that even experienced desert hikers wouldn't be hellbent on doing that time of year?
I also have to add that, IMO, there is no reason that anyone *needs* to have a gun hiking in JTNP. There is no need to conjure up scenarios of mountain lions or coyotes (or desert tortoises) attacking people there. The likelihood of an animal attack is so remote as to not even be worth mentioning. You would be much more likely to encounter a two-legged creature that would threaten your life, but if that occurred with any measurable frequency, no one would want to hike there. JTNP is far safer than any major American city in that respect, period.
I think JO planned this out from the beginning. He isolated RN out on a trail that he knew was underutilized in the summer, forced her to walk up some poorly traveled area well away from the trail, and then shot her to death followed by his own suicide. There really isn't another reasonable explanation that compares to any other.
I think it is a romantic notion that these deaths were somehow merciful. I think it was just plain old evil at work.
