There is no date on this site, but it specifically notes the difficulty of each road and that "the squeeze" to "heart attack hill" were impassable. I am not sure where that is exactly, but it is my understanding it is near Harper Flat.
borregohiking.com
I watched videos of Jeeps doing Heart Attack Hill and The Squeeze, which are on Pinion Mountain "Road". I saw that Toyota Tacoma video, too.
This is the sort of stuff you do with other people and vehicles so that you don't cause severe damage to your daily driver and are marooned, without another vehicle to drive you back to safety. And certainly not in the height of July heat, in an area where getting marooned or injured can mean death from hyperthermia before you even get dehydrated.
In looking at the routes to Harper Flat, I'm curious about how people think they drove to the Harper Flat area:
1. Pinion Wash Road from Highway 78 to Nolina Wash looks to have several very rocky areas.
@mark1969 Based on what has been posted here, IMO the truck was disabled somewhere in the purple area because there is a fence that blocks vehicle access to Harper Flat. The fence can be
seen here on Google Maps. The foot route of escape is the yellow line toward Harper Canyon. Remains location is marked per reports (5 miles from the truck as the crow flies). The wash area away from Harper Canyon Trailhead and toward Hwy 78 (as described here where the backpack was found) would be that large
yellow wash area flowing away from Harper Canyon and the remains.
View attachment 456439
Below is the same map turned around showing the location of Hwy 78 better. The search area should be the yellow wash area IMO unless FJ stayed with the truck. But the discovery of her backpack (seemingly in the yellow wash area) would make that area a priority IMO.
View attachment 456440
borregohiking.com
I've been torturing myself all day trying to reconcile that I Hike San Diego trip report and maps with where the remains were found. Until I realized the I Hike San Diego report was actually hiking Pinyon Mountain Wash, and not really the Harper Canyon area where the remains were found. I think the Petroglyphs are more in that area, not in the region of the remains. The fence and gate are also in the southwest corner of Harper Flat, and the fence appears to be there to prevent vehicles from driving west on Pinyon Mountain Road where the steep Heart Attack Hill and The Squeeze would cause unsuspecting vehicles to get stuck and require removal.
With this information, it makes sense that they intended to go visit petroglyphs in the Pinyon Mountain area. The most likely route to where the vehicle ended up has them driving south, off of Highway 78 on Pinyon Wash Road. The Hiking report notes that several vehicles got stuck in sand on this route, but they would have made it through onto the Harper Flat area. Perhaps the conditions had changed or he was on a variant of the route and damaged the vehicle.
As someone skilled and self-reliant, I don't think they went up the Harper Canyon on the northeast corner of Harper Flat as an exploration. There is a short drive off of Highway 78 that goes south to the northern end of Harper Canyon where there is a picturesque area described as Cactus Garden. Then they could have hiked south farther into Harper Canyon to see the sights. But the vehicle would have been parked on the north end of Harper Canyon, not where it was found.
The south end of Harper Canyon is completely opposite the trailhead, the fence and gate, and the petroglyph region. There are some descriptions of flowers in that region, but it isn't a hike that is particularly notable, and going north up the canyon would mean another hike back down to the vehicle. And this last hike would have been in the blast-furnace heat of late day or possibly in the evening.
However, if you had damaged your vehicle and were unable to drive back out, this might appear to be a reasonable route to Highway 78. This could explain why her backpack is reported to be found north-east of the Harper Canyon (yellow area in the map in the link). I have to seriously consider that they needed to leave the vehicle and were looking to getting help via the apparent closest trail in Harper Canyon, but something went seriously wrong. Lost their water? Heat stroke? Serious fall with fracture or head injury? Did she have footwear suitable for rough hiking over rocks? Were there any water bottles found anywhere in the region?
Personally, I would have thought to retrace the route I drove in if my vehicle was disabled, following tire tracks in Pinyon Wash back to Highway 78. But he was clearly experienced and resourceful, and until we find more about her or the specifics of the vehicle when it was located, or the contents of her backpack, can only speculate about their thinking.
It goes without saying that I don't think he had any intention of hurting her or a murder-suicide.