NBC News 7 San Diego reports Mustaine spoke about the disappearance and search for the 75-year-old, who was last seen around 4 p.m. on October 4 at the Pinezanita RV Park and Campgrounds on Highway 79 in Julian, about 60 miles east of downtown San Diego.

Estabrook's husband noticed she was gone when he returned from a shower and couldn't find her. "Sally Estabrook went missing Saturday at 4 p.m. up at the Pinezanita Campground up in Julian," said Mustaine. "She has Alzheimer's, severe, [and] she's not communicative. And we're just asking everybody right now, because of the search and how extensively that it's gone, we're looking outside of the camp area now. And we're just asking everybody that may have been up there to take a look in your sheds, in your garages, any of the thick brush around your house. A lot of times, people that wander that have Alzheimer's are found very close to their home. They just take shelter underneath bushes and stuff. So we're asking that you look there."

"Also, anybody that's working in the medical field, in the hospitals and shelters, any of the senior citizens, adult homes, stuff like that, look at your patients," added Mustaine. "Maybe there's somebody there that's not supposed to be there. We need your help. For any of you that are watching this right now, we're just asking that if you see Sally - we call her nana - she's probably not gonna answer to you, just call 911 and then we'll go from there."

Mustaine said the search for Estabrook has intensified over the past few days, with search and rescue crews now looking in areas outside the Julian campground for any traces of the missing woman.