I think I read earlier in this thread that LE has stated without question that this is not a case of burglary gone wrong. That is unfortunate, because that is exactly what it looks like. In doing this they may be focusing on DNA of an alleged perpetrator and all the time it takes to get it, rather than the location of a medically compromised 84 yr. old woman, who must be in dire straits physically at this point.
I hope this is just a cover up ruse by police and they are actually examining the burglary aspect, or precious time will be wasted.
If this was a bungled burglary by a non-professional, he will have panicked and likely separated himself from her as quickly as possible. I hope there are search teams combing the desert with drones, FLIR, and SAR teams.