Thanks for the up dates and thanks for your great efforts to recover the individuals.
As a side note, Border Patrol trackers usually use the "sign cutting method" and would have jumped to the next wash, sandy area, or dirt ravine (people leave sign when going up and down the sides of ravines) if they lost the track due to rocky terrain. In regards to rocky terrain, an expert direct tracker can usually find traceable sign in these areas via "sign cutting" on a closer scale to follow a track relatively directly unless the individual is deliberately trying to evade him.
All that aside, I think too many well meaning searchers may have obscured the tracks left by the couple. As some or many areas only allow for beach divots type tracks, identifying what tracks were the couple's, left by searchers, or earlier hikers would be difficult. In short, I wish search coordinators had called the Border Patrol earlier. They can assemble teams of expert trackers very quickly. Tono' Odham nation police also have a team of expert trackers as well.