I think this is not quite a good development, personally I feel it just giving more mystery without resolving anything, though.
Well, it's not bad, it just left the readers at the edge of their sit, so it's not bad.
But I fear it will all just resolve with a rushed ending, or even worse, only 1 chapter to solve it all.
Come on who is suspicious, everyone, but are they?
Who is this psycho girl?
Is this really a work of a single girl?
What the heck just happened?
And I also feel like the story is quite, a bit forcing, at introducing a new plot, like at the end,
Why is this girl took a picture of them from behind the bush, and from such a far away, the screen of that girl is clear to view. Hmm...
And if she already knew that girl is suspicious, why not try, warning the guys? Or whatever.