Diana Mae Mattingly, 64, was last seen December 12, 2020, at the Butterfield Ranch RV Resort along county Highway S2 in the high desert near Anza-Borrego. Neighbors say she lived there and that Lisa Nellom, who had been helping with daily tasks and doctor’s appointments, reported her missing. Mattingly reportedly suffered from dementia and Alzheimer’s disease and had been confused and distressed in the days before she disappeared, saying she wanted to travel to Las Vegas and worrying about missing New Year’s celebrations.

Deputies responded to a missing person report on December 15 at the 14000 block of Great Southern Overland Stage Route. A church member may have seen her walking north in Shelter Valley on December 13, and investigators learned she was trying to get a ride to Ramona or El Cajon. The Sheriff’s Department classified her as missing at risk and said there was no indication of foul play; it did not confirm the dementia diagnosis or issue wide public alerts. Friends and neighbors have criticized the scope of the investigation. The case is open in NamUs as MP145611 with no confirmed sightings or developments to date.

If anyone knew Diana, her routines, or saw her in Shelter Valley, Ramona, or El Cajon in mid-December 2020, please share information.