DAVE MUSTAINE On His Mother-In-Law's Disappearance: 'My Wife Is Very, Very Upset'

MEGADETH mainman Dave Mustaine spoke to KFMB about the search for his missing mother-in-law, who is suffering from Alzheimer's disease.

75-year-old Sally Estabrook was last seen at a campground near Julian, California Saturday afternoon, a sheriff's spokeswoman said Sunday. Her husband noticed she was gone when he returned from a shower and couldn't find her.

"As you can imagine, they're pretty distraught," Dave said about how his family is dealing with his mother-in-law's disappearance. "My wife is very, very upset. I think, with [my mother-in-law] having Alzheimer's, it complicates it so much."

"We miss her. We want to come back. We want to find her," Dave's son — and Sally Estabrook's grandson — Justis Mustaine told KGTV.

The MEGADETH leader and his wife, Pam, Estabrook's daughter, lived in Fallbrook, California — one hour north of San Diego — until they moved to Tennessee just last week. All of them flew back to California upon learning of Estabrook's disappearance.

"[Dave is] in shock. We're all in shock. She's been out there two nights already, no food, no water, nowhere to sleep. We just hope she's alright," Justis Mustaine told KGTV.

Estabrook is 5 feet 4 inches tall, about 145 pounds with shoulder-length, blond hair. She was last seen wearing a teal top and white, Capri pants.

Because Estabrook suffers from Alzheimer's, she isn't very communicative, but might respond to her name.

Anyone who sees Estabrook should call 911 or the sheriff's department at (858) 565-5200.

Mustaine revealed last year that a lot of the songwriting process for MEGADETH's 2013 album, "Super Collider", was affected by the fact that he had just found out his mother-in-law had Alzheimer's disease. He told Loudwire: "Until it happens to you, you really have no idea. And I think that when I saw how upset our family became and yet how we are able to provide the resources for her, it made me think about all the families going through this that don't have the resources to take care of a loved one. It also made me really appreciate our fans, because without them, I would not be able to take care of things the way I am. It really brings it all home. And then beyond that, I just did what any good artist does. I put my emotions into my music. That's the pain you hear in the music. It's real. People can say, 'We don’t want to hear this kind of shit,' but to me, this shit is important."

According to Mustaine, the "Super Collider" track "Forget To Remember" was written specifically about some experiences with memory and forgetting that have come very close to home.

"The sad thing about Alzheimer's disease is it's like watching an ice sculpture of somebody you love melt in front of your eyes; it's really, really painful," he told the "Shockwaves" podcast. "So the song has a double entendre where there's a guy and he talks to a girl in the song and it's kind of like the movie 'The Notebook' where the character in the movie, the female, comes in and out of Alzheimer's and she is present and she is back in La La Land again. So you don't really know in this song if it's a girl that is intentionally trying to forget a relationship with a guy or if it's somebody who has Alzheimer's disease, which, really, is what it's about. I worded it so that it could be either way."