Sally Estabrook, 76, disappeared three weeks ago from her home in Julian, California. She's suffering advanced-stage Alzheimer's and, says the Megadeth mainman, "couldn't put three words together."

A search led by police assisted by 300 volunteers found nothing nearby, leading Mustaine to believe that someone may have given Sally a lift, and is now uncomfortable about coming forward.

He tells 101KGB: "There's no way a 76-year-old woman can trek all the way down a mountain like that. So somebody was being nice and trying to help her. We're thinking the person who tried to help her is afraid that maybe they did something wrong.

"Even the most terrible of convicts still has a mother. The person could have pulled over and helped her, and have a criminal past and can't say anything."