Something simply doesn't sit right with me and this letter. It seems all too convenient. While I would like to believe Abby wrote this, I think it's simply wishful thinking on everyone's part. Sending a letter to her mother's PO box ( or ANY PO box) seems... strange (unless, of course, that's where all of their mail went, in which case, not as strange). But why not a call? Wouldn't that be the quickest & easiest form of communication? And a much more convincing "I'm okay?"
Do I think Abby is alive? I do.
Personally, I think we're dealing with a case similar to Elizabeth Smart or the kidnappings of Ariel Castro.
I believe the perp knows what he's doing (most likely this isn't his first) & is playing with LE, who sadly, I don't believe have much to go on. IMO
I'm not that much older than Abby and remember 15 quite well. Abby isn't your "typical" runaway. She has a social media presence. She is close with God. She has a boyfriend (and you know how teen romances are). I don't buy she would willingly leave all of that behind, especially for 2 months.
At 15, I remember all of the sketchy places & shortcuts my friends & I ventured after school. Did our parents know? NOPE! At 15, you feel invincible. To walk through the woods or a back alley didn't seem dangerous. Now? Hell yeah.
And another thing I wanted to throw out, is a possibility of why she had her handbag with her. At my high school, we weren't typically allowed to carry backpacks around from class to class. They were to be left in our locker until we were dismissed at the end of the day. Handbags for girls were allowed, though, for personal items and such. Not all girls carried one, but most did, and then would shove it in their larger backpack, along with textbooks, when leaving.
