I read this and remembered a time in my family growing up when my mom was probably about the same exact age as Gail, She had no history of mental illness, But something to do with hormones and Menopause symptoms, had her acting extremely paranoid. She believed my dad was trying to poison her, she wouldn't eat the food or drinks he made.
I know my dad very very well, and we are extremely close and he would never do something like that. She believed he was cheating and trying to kill her, and said she felt like she was going crazy. If you research Menopause and paranoia, you will find a lot of information. When I read about Missing Persons, I usually get an impression or feeling about what might have happened, I am thinking this could be a case where something like what happened with my mom, is going on.