Jason, I am really sorry your dad passed this way. And so sorry, too, that you hadn't communicated with him for so long. If it is any consolation, he was out doing what he wanted to, and it appears, really enjoying life. How many other 75 year olds can do that?
As for the picture, it actually came from another website, High Sierra Topix, where it was reportedly first posted on a "California Peaks" Facebook page. You might join those groups/forums and try to get more info. Here is the link where I found the picture:
Missing Hiker in Sequoia National ParkSequoia National Park report he was found on the north slope, at 13,100' elevation. People practically never go to that side of the mountain, because it is treacherously steep. Unfortunately, from the top, it doesn't start out that way. This is purely my speculation, but a possible scenario is this: Dawson was tired after summiting, and looking at a map, may have thought he could take a shortcut off the north side of the mountain, and head down more quickly to his camp at Crabtree Meadow. The trail goes almost 2 miles south from the summit, then winds its way down past Guitar Lake and then wanders down to Crabtree Meadows. It is definitely a circuitous route, but that is what everyone uses to get down to Crabtree.
If Dawson committed to a north-side shortcut, he could have done ok descending the first 500 feet in elevation. But after that, it gets really steep, with bare rock. He may have attempted to down-climb that, and all it would take is one slip. In his state: tired, high altitude, low oxygen, making a tiny mistake, or even stepping on a loose rock, could lead to disaster. I am only guessing, but that may have been what happened. It was a tragedy, and I am very very sorry.
Now, for some reality: Contrary to what the dispatcher you spoke with knew, others have indeed died on that slope. It is more often due to their slipping or failing to control a slide in icy conditions, but it DOES occur on the north slope of Mt Whitney. You see, there is a "Mountaineers Route" that starts down from the top on the north side. However, after descending about 400 feet, the route turns abruptly eastward, and goes through "The Notch", and descends to Iceberg Lake, just east of the summit massif.
I know of one person who successfully ascended Mt Whitney via that side, and I know a guide book reports it can be done. I looked at going up that way two years ago, and stayed off of it because it looked too treacherous. At that time, I realized the fellow who HAD climbed it did it when the slope was covered with snow in spring, so he was able to use crampons and ice axe, which enable climbers to ascend extremely steep slopes. It is too steep to climb when the rock is bare.
Jason, I hope you get through these tough times ok. Please get together with your living family members, and pass along the sincerest condolences that I can assure you everyone here wants to offer.
May Dawson Johnson rest in peace.