Hi, I've read through all the threads here and what's been available to the public, including the 911 calls. I have also visited the area a couple weekends ago. Here are my questions that I hope someone can answer.
1. What parts of the canyon were searched? (Or better yet, what has the SDPD and PI already done/checked so any new search or research is not repeated?)
2. What building specifically had the last known surveillance footage of Lance?
3. What type of phone did he have? Has anyone (your PI?) asked lost/found in the surrounding buildings?
Based on the 911 calls, it seems Lance was in the line of sight of 402 Dickinson. This building has "glass corners" on two sides. One facing the Central Plant and one facing westbound Dickinson/Canyon area.
Looking at all the information, I think the Central Plant area and surrounding canyon between it and 402 Dickinson Street should be searched if it hasn't and Central Plant workers should be interviewed again. There is a fence in some parts, but not all. This area has a VERY loud, steady whooshing sound you can hear across the canyon and is cluttered and disorienting even for those walking in daylight and in good health. If he was trapped in a building in this area (911 call), this is the likeliest area that he may not be noticed for 2 years. If he was in this area and left on foot, he could have fallen into the canyon here or become injured in some type of equipment or machinery and again may not be noticed based on the cluttered/construction area and tiered landscape.
Secondly, the canyon area at the curve of Dickinson should also be checked. I am not certain if this is the area the gentleman who fell years prior was found, but it is definitely the area that the news footage from his story showed the searchers. It is easy to walk right into the canyon from here, and it is obvious (littered with debris) transients use this as a path into the canyon. This area is also in the line of sight of 402 Dickinson glass corners.
All in all, despite how Google Earth makes it appear, this canyon is NOT that big and the space between these areas seems accessible to, at the very least, drones and probably dogs and foot searches as well. There are few high trees, lots of chapparal and I think a drone search would be a good way to search the area again, starting in the two locations I mentioned above if they haven't been searched well yet. You would need to go through the proper process for a drone search, as the hospital has a Heliport, but when I visited on a Saturday afternoon, the entire back area was completely deserted except for a few cars at the Bannister House and a couple workers at the Central Plant. This area behind the hospital is a Mon-Fri office area and a weekend search would be least disruptive. (Note: I would mention there are quite a few transients in the area, so I advise cognizance, safety, and sensitivity regarding those in the area if you search.)
Finally, if you haven't submitted this story to the Vanished podcast, I recommend it if you want more coverage and publicity. This is exactly the type of cases she covers and it would get more pressure on LE, if needed, to continue looking and more exposure to the public bolo as well.