I wish I could answer some of these questions, but quite frankly, I'm confused, too.
My experience with family members who are drug users is they may go several days, even a week, but usually make contact with someone.
I also believe her mom has not heard from her. They're going crazy, can't sleep, etc, so that's sincere.
I don't know exactly why she might think she was in trouble. She's flirted with trouble by her drug use and connections there, so that's really not unusual.
I was aware that her mom thought she was leaving for at least overnight, but I wasn't sure I was allowed to say so since I had not seen it being said anywhere else. There was no fight or anything like that with her mom, and her brother has since been released from jail, so there's no reason to explain why she wouldn't at least call her mom if she is able to. She also didn't indicate that she thought she needed to hide for any reason.
I can see why the Mobile LE believes she is just gone on her own free will, but I can also see why that is hard to believe. If it wasn't going on a month now, it might be easier to believe she's just staying with a friend. But that wouldn't explain her not being in contact with her family, especially if she was still in the area--she would have heard about DH's death and would want to be with her family. As dysfunctional as they are, they do love each other.